Surgical retractor blade and system

0001This application is a continuation of application Ser. No. 09/305,811, filed May 4, 1999 now issued as U.S. Pat. No. 6,282,912.

FIELD OF THE INVENTION

0002The present invention relates generally to surgical instruments, and more particularly to surgical retractor, instrument mount, and tissue stabilizer devices for use during coronary artery bypass graft surgery.

BACKGROUND OF THE INVENTION

0003Diseases of the cardiovascular system affect millions of people each year and are a leading cause of death throughout the world. The cost to society from such diseases is enormous both in terms of the number of lives lost as well as in terms of the costs associated with treating patients through traditional surgical techniques. A particularly prevalent form of cardiovascular disease is a reduction in the blood supply leading to the heart caused by atherosclerosis or other condition that creates a restriction in blood flow at a critical point in the cardiovascular system that supplies blood to the heart.

0004Treatment of such a blockage or restriction in the blood flow leading to the heart is, in many cases, treated by a surgical procedure known as a coronary artery bypass graft (CABG) procedure, more commonly known as a “heart bypass” operation. In the CABG procedure, the surgeon “bypasses” the obstruction to restore normal blood flow to the heart either by attaching an available source vessel to the obstructed target coronary artery or by removing a portion of a vein or artery from another part of the body, to use as a graft, and installing the graft between a point on a source vessel and a point on a target artery.

0005To restore the flow of blood to the heart, the CABG procedure requires that a fluid connection be established between two vessels. This procedure is known as an “anastomosis.” Typically, a source vessel, such as a source artery with an unobstructed blood flow, i.e., the left internal mammary artery (LIMA), or a bypass-graft having one end sewn to an unobstructed blood source such as the aorta, is sewn to a target occluded coronary artery, such as the left anterior descending (LAD) artery or other vessel, that provides blood flow to the muscles of the heart.

0006Although the CABG procedure has become relatively common, the procedure itself is lengthy and traumatic and can damage the heart, the cardiovascular system, the central nervous system, and the blood supply itself. In a conventional CABG procedure, the surgeon makes an incision down the center of the chest, cuts through the sternum, performs several other procedures necessary to attach the patient to a heart-lung bypass machine, cuts off the blood flow to the heart, and then stops the heart from beating in order to complete the bypass. The most lengthy and traumatic surgical procedures are necessary, in part, to connect the patient to a cardiopulmonary bypass (CPB) machine to continue the circulation of oxygenated blood to the rest of the body while the bypass is completed.

0007In recent years, a growing number of surgeons have begun performing CABG procedures using surgical techniques especially developed so that the CABG procedure could be performed while the heart is still beating. In such procedures, there is no need for any form of cardiopulmonary bypass, no need to perform the extensive surgical procedures necessary to connect the patient to a cardiopulmonary bypass machine, and no need to stop the heart. As a result, these beating heart procedures are much less invasive and the entire procedure can typically be achieved through a small number, typically one or two, comparatively small incisions in the chest.

0008Despite the advantages, the beating-heart CABG procedure is not universally practiced, at least in part, because of the difficulty in performing the necessary surgical procedures using conventional surgical instruments. For example, it has been difficult for the surgeon to access the required areas of the heart requiring revascularization. In addition, the various surgical steps that are required to be performed on the heart itself are more difficult to perform because the heart muscle continues to move and contract to pump blood throughout the duration of the procedure.

0009The specific portion of the surgical procedure that creates the anastomosis in the beating-heart CABG procedure is particularly difficult. Completion of the anastomosis requires placing a series of sutures through extremely small vessels on the surface of the heart while the heart muscle continues to beat. Moreover, the sutures must be carefully placed to ensure that the source vessel or graft is firmly attached and will not leak when blood flow through the vessel is established. In cases where the target coronary artery is temporarily obstructed, for example, to improve the surgeon's visibility and avoid excessive blood loss, it is also important that the anastomosis procedure be performed rapidly to avoid ischemic damage to the heart.

0010Further adding to the difficulty of the procedure is the fact that the working space and visual access are often quite limited. The surgeon may be working through a small incision in the chest, for example, or may be viewing the procedure on a video monitor if the site of the surgery is viewed via surgical scope. The vessel, and particularly the arteriotomy to which a source vessel is to be anastomosed, may also be very difficult for the surgeon to see as it may be obscured more or less by layers of fat or other tissue.

0011The beating-heart CABG procedure could be greatly improved if the heart could be accessed and stabilized during the procedure such that the motion of the heart, particularly at the site of the anastomosis, is minimized even though the heart continues to beat and supply blood to the body. The beating-heart CABG procedure could be further improved if the target vessel, and specifically the arteriotomy was presented to the surgeon in a way that allows sutures to be easily placed.

0012In view of the foregoing, it would be desirable to have improved devices for accessing and effectively stabilizing the beating heart at the site of the anastomosis. It would be desirable to have a retractor system that provides unobstructed and organized access to the areas of the heart requiring revascularization. It would be further desirable to have a low-profile, atraumatic stabilizing device that stabilizes the beating heart at the site of the anastomosis and provides a favorable presentation of the target vessel and the arteriotomy. It would be further desirable to provide a mount for the stabilizing device, or other instruments, that allows the stabilizing device to be easily maneuvered to the desired position and orientation, fixedly secured until the procedure is completed, and then easily removed from the site of the anastomosis.

SUMMARY OF THE INVENTION

0013The present invention will be described for use in performing CABG surgery, but the invention is not limited thereto, and is contemplated to be useful for other surgical procedures requiring access through an incision into a patient.

0014The present invention involves various aspects of a surgical retractor for use, for example, in performing a CABG procedure on a beating heart. The present invention may involve a surgical retractor platform blade which facilitates the creation of a working opening through an incision in a patient, such as a sternotomy, and may also provide a platform for securely mounting various instruments or for organizing such things as sutures. The present invention may also include an instrument mount which may be secured to the platform.

0015One aspect of the present invention involves a surgical retractor blade for attaching to a drive mechanism for use in spreading apart opposite sides of an access incision in a patient. The retractor blade may have a unitary body which includes a first end, a second end, and a channel adapted to engage one side of an incision in patient, preferably an incised sternum. The body is preferably polymeric, but may be metal, a composite material, or other suitable substantially rigid, load bearing material. The first end preferably has a cavity adapted to receive a support member extending from said drive mechanism. In one embodiment, the first cavity is a blind hole having a predetermined depth from the first end. Preferably, the depth is at least about 1.125 inches. The cavity may be tapered, becoming progressively smaller in a direction away from the first end. The retractor blade may have a second cavity adapted to receive a second support member extending from the drive mechanism.

0016Another aspect of the present invention involves a surgical retractor blade having a polymeric body having a channel adapted to engage one side of an incision in a patient and a rail extending along at least a portion of the polymeric body. The surgical retractor blade is preferably removably attachable to a drive mechanism. Preferably, the rail has a top portion and bottom portion, the bottom portion having a narrowed region adjacent the top portion thus forming first and second tabs on said top portion. Preferably the rail is curved along its length. The surgical retractor blade may have a cavity, preferably in the form of a tapered hole, adapted to receive a support member extending from a drive mechanism.

0017The surgical retractor may further include a plurality of open slots for receiving a suture therein. The open slots preferably have an internal wall and a suture locking member having a fixed end and a free end, the free end engaging the internal wall so as to clamp a suture placed between the free end and the internal wall. Preferably, the suture locking member is substantially rigid and pivots about its fixed end. The invention may also include a spring member biased against the suture locking member to forcibly urge the free end towards the internal wall.

0018In one embodiment of the retractor blade, at least one of the open slots has a first slot section which bifurcates into a second slot section and a third slot section. Preferably, each of the second and third slot sections has an internal wall and a suture locking member having a fixed end and a free end, the free end engaging the internal wall so as to clamp a suture placed between the free end and the internal wall.

0019In a preferred embodiment, the retractor blade may include a soft tissue retainer for covering or retaining the soft tissue surrounding the incision site. In a preferred embodiment, the soft tissue retainer may be a flexible polymeric flap extending from the body of the retractor blade. The polymeric flap is adapted to flexibly engage and soft tissue and fat to keep them away from the platform area of the retractor body. The flexible polymeric flap is preferably injection molded over a portion of the retractor blade body.

0020These and other features of the present invention will become more fully apparent from the following description and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

0021<figref idref="DRAWINGS">FIG. 1</figref> is a perspective view illustrating a cardiac surgery system according to the principles of the present invention.

0022<figref idref="DRAWINGS">FIG. 2</figref> is a perspective view illustrating a retractor assembly according to the principles of the present invention.

0023<figref idref="DRAWINGS">FIG. 3</figref> is a perspective view illustrating a preferred retractor drive assembly.

0024<figref idref="DRAWINGS">FIG. 4</figref> is a perspective view illustrating an exemplar bar assembly.

0025<figref idref="DRAWINGS">FIG. 5</figref> is a perspective view illustrating a moveable housing associated with the retractor drive.

0026<figref idref="DRAWINGS">FIG. 6</figref> is a perspective view illustrating a retractor drive handle assembly.

0027<figref idref="DRAWINGS">FIG. 7</figref> is a top plan view illustrating a preferred platform blade and retractor drive assembly in an unengaged position.

0028<figref idref="DRAWINGS">FIG. 8</figref> is a top view in partial cross-section illustrating the platform blade and retractor drive assembly in an engaged position.

0029<figref idref="DRAWINGS">FIG. 9</figref> is a cross-sectional view taken along line <b>9</b>—<b>9</b> shown in <figref idref="DRAWINGS">FIG. 8</figref>.

0030<figref idref="DRAWINGS">FIG. 10</figref> is a partial top view illustrating a preferred suture stay arrangement associated with a platform blade.

0031<figref idref="DRAWINGS">FIGS. 11A</figref>, <b>11</b>B, and <b>11</b>C illustrate a preferred platform blade latch.

0032<figref idref="DRAWINGS">FIGS. 11A and 11B</figref> are top and front plan view, respectively.

0033<figref idref="DRAWINGS">FIG. 11C</figref> is a cross-sectional view taken along line <b>11</b>C—<b>11</b>C as shown in <figref idref="DRAWINGS">FIG. 11B</figref>.

0034<figref idref="DRAWINGS">FIG. 12</figref> is a perspective view showing a preferred suture lock.

0035<figref idref="DRAWINGS">FIG. 13</figref> is a perspective view illustrating an instrument mount assembly according to the principles of the present invention.

0036<figref idref="DRAWINGS">FIG. 14</figref> is an exploded assembly illustration of the instrument mount assembly of <figref idref="DRAWINGS">FIG. 13</figref>.

0037<figref idref="DRAWINGS">FIGS. 15A and 15B</figref> are perspective views illustrating the assembly of the mount cam to the mount base.

0038<figref idref="DRAWINGS">FIGS. 16A and 16B</figref> are top and front plan views, respectively, illustrating a preferred mount cam.

0039<figref idref="DRAWINGS">FIG. 17</figref> is a front plan view illustrating a preferred mount hinge.

0040<figref idref="DRAWINGS">FIG. 18</figref> is an exploded view illustrating the assembly of the mount body to the mount base.

0041<figref idref="DRAWINGS">FIG. 19</figref> is an exploded view illustrating the assembly of the instrument clamp to the mount body.

0042<figref idref="DRAWINGS">FIG. 20</figref> is a cross-sectional view taken through a horizontal plane of the instrument shaft grip of <figref idref="DRAWINGS">FIG. 19</figref>.

0043<figref idref="DRAWINGS">FIG. 21</figref> is a front plan view showing an assembled instrument mount operably positioned on a platform blade according to the principles of the present invention.

0044<figref idref="DRAWINGS">FIGS. 22A and 22B</figref> are front and top plan views, respectively, of an alternate instrument mount assembly according to the principles of the present invention.

0045<figref idref="DRAWINGS">FIG. 23</figref> is a cross-sectional view taken along line <b>23</b>—<b>23</b> as shown in <figref idref="DRAWINGS">FIG. 21</figref>.

0046<figref idref="DRAWINGS">FIG. 24</figref> is an offset cross-sectional view taken along line <b>24</b>—<b>24</b> as shown in

0047<figref idref="DRAWINGS">FIG. 22</figref> illustrating the mount assembly of <figref idref="DRAWINGS">FIGS. 21 and 22</figref> in the closed position.

0048<figref idref="DRAWINGS">FIG. 25</figref> is an offset cross-sectional view illustrating the mount assembly of <figref idref="DRAWINGS">FIGS. 21 and 22</figref> in the open position.

0049<figref idref="DRAWINGS">FIG. 26</figref> is an exploded assembly view showing selected components of a preferred closing mechanism.

0050<figref idref="DRAWINGS">FIG. 27</figref> is a perspective view illustrating a preferred instrument mount cam post.

0051<figref idref="DRAWINGS">FIG. 28</figref> is a perspective view illustrating a preferred instrument mount release button.

0052<figref idref="DRAWINGS">FIG. 29</figref> is a perspective view illustrating a preferred instrument mount follower post.

0053<figref idref="DRAWINGS">FIG. 30</figref> is a perspective view of a preferred instrument mount shaft clamp.

0054<figref idref="DRAWINGS">FIG. 31</figref> is a perspective view of a preferred instrument mount conical clutch.

0055<figref idref="DRAWINGS">FIG. 32</figref> is a perspective view of a threaded collar associated with the instrument mount shaft clamp.

0056<figref idref="DRAWINGS">FIGS. 33 and 34</figref> are exploded perspective and cross-sectional views respectively of a handle mechanism of a preferred tissue stabilizer.

0057<figref idref="DRAWINGS">FIG. 35</figref> is an exploded perspective view of a contact member of the stabilizer shown in <figref idref="DRAWINGS">FIGS. 33 and 34</figref>.

0058<figref idref="DRAWINGS">FIG. 36</figref> is a rear plan view of the contact member of <figref idref="DRAWINGS">FIGS. 33</figref>, <b>34</b> and <b>35</b>.

0059<figref idref="DRAWINGS">FIG. 37</figref> is a cross-sectional view of the contact member of <figref idref="DRAWINGS">FIG. 36</figref> taken along line <b>37</b>—<b>37</b>.

0060<figref idref="DRAWINGS">FIG. 38</figref> is a perspective view illustrating a stabilizer base embodiment having an offset shaft connection.

0061<figref idref="DRAWINGS">FIG. 39</figref> is a perspective view illustrating an alternative offset stabilizer base in use over a target vessel.

0062<figref idref="DRAWINGS">FIGS. 40A and 40B</figref> are respectively front and side plan views of the offset stabilizer base embodiment of <figref idref="DRAWINGS">FIG. 39</figref>.

0063<figref idref="DRAWINGS">FIG. 41</figref> is a perspective view of a tissue stabilizer having a moveable ball/post.

0064<figref idref="DRAWINGS">FIG. 42</figref> is a perspective view illustrating another tissue stabilizer embodiment having a moveable ball/post.

0065<figref idref="DRAWINGS">FIG. 43</figref> is a partial cross-section taken through the ball/post of <figref idref="DRAWINGS">FIG. 42</figref> showing a spring biased ball/post.

0066<figref idref="DRAWINGS">FIG. 44</figref> is a partial cross-section showing the ball/post of <figref idref="DRAWINGS">FIG. 43</figref> utilizing a locking clip to secure the ball/post.

0067<figref idref="DRAWINGS">FIG. 45</figref> is a perspective view of the locking clip of <figref idref="DRAWINGS">FIG. 44</figref>.

0068<figref idref="DRAWINGS">FIG. 46</figref> is a perspective view illustrating another moveable ball/post stabilizer embodiment.

0069<figref idref="DRAWINGS">FIG. 47</figref> is a front perspective exploded view of a stabilizer base assembly having an adjustable ball/post position.

0070<figref idref="DRAWINGS">FIG. 48</figref> is a rear perspective view of the stabilizer base of <figref idref="DRAWINGS">FIG. 47</figref>.

0071<figref idref="DRAWINGS">FIGS. 49A and 49B</figref> are front and rear perspective views of the stabilizer base assembly of <figref idref="DRAWINGS">FIG. 47</figref>.

0072<figref idref="DRAWINGS">FIG. 50</figref> is a partial cross-sectional view through a portion of the rear guide slot of the stabilizer base of <figref idref="DRAWINGS">FIG. 47</figref>.

0073<figref idref="DRAWINGS">FIG. 51A</figref> is a perspective view of a stabilizer base embodiment having a single contact member and bail construction.

0074<figref idref="DRAWINGS">FIG. 51B</figref> is an end plan view of the stabilizer embodiment of <figref idref="DRAWINGS">FIG. 51A</figref>.

0075<figref idref="DRAWINGS">FIGS. 52A and 52B</figref> are perspective views illustrating another stabilizer base embodiment having a single contact member and bail construction.

0076<figref idref="DRAWINGS">FIGS. 53 and 54</figref> are perspective views illustrating stabilizer base embodiments having a single contact member and a bail having a mechanical drive.

0077<figref idref="DRAWINGS">FIG. 55</figref> is a perspective view of a preferred cardiac surgery system during operation according to the principles of the present invention.

DETAILED DESCRIPTION

0078The present invention involves surgical instruments for accessing and stabilizing the heart and methods for their use. The present invention may involve a retractor system or assembly for accessing the heart. The present invention may also include a mount that allows various instruments to be easily positioned within the surgical working space, locked or secured into a desired position for the duration of a particular surgical procedure, and then easily and safely removed from the working space. According to a preferred embodiment the instrument may be a device to facilitate stabilization of the heart during coronary surgery.

0079Although the instruments and methods of the present invention may have application in both conventional stopped-heart and beating heart procedures, they are preferably used to access and stabilize the beating heart during a minimally invasive coronary artery bypass graft (CABG) operation which has been specially developed to facilitate completion of an anastomosis, typically between a target artery and a bypass graft or source artery, without requiring cardiac arrest such as cardioplegia or fibrillation and without cardiopulmonary bypass (CPB). Further, although the instruments for accessing and stabilizing the beating heart can be applied in a number of different surgical contexts involving various incisions and surgical approaches to the heart as are known in the art, the instruments and devices described herein are most advantageously employed in a CABG procedure wherein the heart is accessed through only one or two minimally invasive incisions in the chest.

0080Although the particular source vessel and target artery of the anastomosis are determined clinically, a common minimally invasive bypass procedure on the beating heart includes an anastomosis which forms a connection between the left internal mammary artery (LIMA) as the source artery, and the left anterior descending artery (LAD) as the target artery. To complete the anastomosis, the surgeon must dissect a portion of the LIMA by separating it from the internal chest cavity. Once dissection of the LIMA is achieved, the surgeon may attach the dissected LIMA to the target coronary artery, i.e., the LAD by way of creating an anastomosis.

0081In this example, the present invention may involve a number of discreet components that facilitate access to the anastomosis site, allow various instruments or devices to be maneuvered and secured in place, and provide stabilization of the heart. The retractor of the present invention may be used to provide access to the anastomosis site of the target artery on the heart itself. The various stabilizer embodiments of the present invention may be used to stabilize the beating heart during at least the portion of the procedure during which the surgeon completes the anastomosis of the LIMA to the LAD. The mount of the present invention may be used to facilitate convenient manipulation of the stabilizer, and other instruments or devices, to their desired position and allows the devices to be secured in that desired position. Although the LIMA to LAD anastomosis is provided as one example, it is readily appreciated that the techniques and instruments described herein may be applied to other procedures depending on the clinical diagnosis and the patient's anatomy.

0082Although each component of the present invention may be used separately with great benefit, the components are preferably used in unison to provide a surgical system which provides an unobstructed and organized surgical field, exceptional instrument maneuverability and access to the heart facilitating total revascularization of the heart if required, and effective vessel stabilization during the anastomosis procedure. Although the present invention will have application whether access to the heart is achieved by way of a full-sternotomy, mini-sternotomy, para-sternotomy, thoracotomy or other known approach, the exemplar embodiments described below will be generally described with reference to a coronary artery bypass procedure using a mid-sternal approach.

0083Referring to the figures wherein like numerals indicate like elements, an exemplar surgical system for performing a mid-sternal surgical procedure on the beating heart is illustrated in <figref idref="DRAWINGS">FIG. 1</figref> and includes retractor assembly <b>10</b>, mount assembly <b>20</b> and stabilizer assembly <b>30</b>.

0084Retractor assembly <b>10</b> generally includes a pair of opposing blades adapted to engage opposite sides of a sternal incision, or other incision, and a drive mechanism constructed to force the blades, and thus the sternum apart. Using the drive mechanism, the sternum may be spread to the desired opening, thus providing the desired access and direct visualization of the thoracic cavity. If desired, the heart may be positioned or oriented to best present the target vessels for anastomosis. This positioning may be established, for example, through the strategic placement and tensioning of sutures in the pericardial sac, by appropriately placing the patient in the Trendelenburg position, or by using a heart positioner in the form or a strap or pad or the like.

0085Once the target vessel is in the desired position, at least one component of stabilizer assembly <b>30</b> is brought into contact with the beating heart adjacent the target site of the anastomosis. The surgeon then applies a stabilizing force to the beating heart via the stabilizer assembly <b>30</b> which may then be fixed in place, preferably to the retractor assembly <b>10</b> by way of mount assembly <b>20</b>. The stabilizing force supplied by the stabilizer assembly substantially eliminates movement of the heart in the area of the anastomosis so that the surgeon may accurately and efficiently perform the required anastomosis (or other surgical procedure). After the anastomosis has been completed, the stabilizing force is released and the contacting component of stabilizer assembly <b>30</b> is removed from the anastomotic site.

0086Each of the principal components, the preferred surgical system, and their methods of use are separately described in detail below. A preferred retractor according to the principles of the present invention is described below with reference to <figref idref="DRAWINGS">FIGS. 2–12</figref>. A preferred stabilizer or instrument mount according to the principles of the present invention is described below with reference to <figref idref="DRAWINGS">FIGS. 13–32</figref>. Preferred stabilizer embodiments according to the principles of the present invention are described below with respect to <figref idref="DRAWINGS">FIGS. 33–44</figref>. A preferred surgical system and methods for performing a coronary artery bypass on a beating heart according to the principles of the present invention is described below with respect to <figref idref="DRAWINGS">FIG. 45</figref>.

0087The Retractor

0088According to the principles of the present invention, the retractor generally involves a drive mechanism and a pair of opposing blades adapted for insertion into an incision and for engaging opposite sides of the incision. The drive mechanism functions in some manner to urge the opposing blades apart, thus forcing opposite sides of the incision open to allow surgical access through the incision. For purposes of performing a coronary artery bypass, the incision may be any suitable incision which provides the desired access to the thoracic cavity, and more specifically a desired area of the heart. For purposes of example only, the retractor of the present invention will be described with respect to a mid-sternal incision, however skilled artisans will recognize that many aspects the invention are equally applicable to other surgical approaches to the heart, for example, by way of a thoracotomy, or other suitable access approach.

0089When the heart is accessed by way of an incision through all or a portion of the sternum, the opposing blades are adapted to be inserted into and engage opposite sides of a sternal incision such that the severed sternum may be forced apart by the action of the opposing blades to create a working space for operating on the heart. Typically, the drive mechanism is constructed to spread the opposing blades apart in a generally parallel fashion, however, the parting motion may also have a significant curvilinear or angular component as well.

0090In one embodiment, the blades may be permanently, integrally, or inseparably formed with a drive mechanism. Preferably however, at least a portion of the blades are separable from the drive mechanism. That is, at least some of the features and functions associated with the retractor blades are allocated to a structural component which is separate, separable, or otherwise detachable from the drive mechanism. The separate component and the drive mechanism may be manufactured independently and then subsequently assembled at the factory or, more preferably, at the point of use.

0091A retractor construction having a separable component allows the features and functions of the drive mechanism to remain separate from the remainder of the retractor assembly and vice versa. This allows a greatly simplified or depopulated drive mechanism and allows the separable component to have a much more sophisticated construction with increased features and functionality. Accordingly, the simplified drive mechanism, which is typically required to be made from a hardened steel, is easier and more economical to manufacture and easier to maintain, clean and sterilize post surgically. Moreover, the separate component can be economically made from materials or processes that allow for the intricate structural features which provide superior functionality.

0092In a preferred embodiment, the drive mechanism is constructed to be resterilized and reused a relatively large number of times, and the feature-rich separate component is constructed to be disposable, i.e. discarded after a single surgical use. Thus, the depopulated drive mechanism, which will be used over and over, can afford to be constructed to be quite robust with a view to materials and manufacturing processes that will support the rigors of such extended surgical service. The separable component, free from the typical functional requirements of the drive mechanism and the service requirements of extended surgical re-use, may preferably be constructed from any number of engineering materials to produce an economical component having the desired features and which may be discarded after a single use if desired.

0093In a preferred embodiment, retractor assembly <b>10</b> comprises a drive <b>12</b> and first and second platform blades <b>14</b> and <b>16</b> detachably connected to drive <b>12</b>, as illustrated in <figref idref="DRAWINGS">FIG. 2</figref>. Preferably first platform blade <b>14</b> and second platform blade <b>16</b> each have one or more channels or engaging members <b>18</b> adapted to engage opposite sides of an access incision. Activation of drive <b>12</b> forces apart first and second platform blades <b>14</b> and <b>16</b> thereby causing engaging members <b>18</b> to correspondingly force the incision open to provide access to the desired surgical site.

0094In the example of a sternal approach to the heart, engaging members <b>18</b> are adapted to engage each side of the incised sternum to reliably hold and engage the sternum as the sternum is forced open to expose the thoracic cavity and ultimately the heart. As best seen in <figref idref="DRAWINGS">FIG. 9</figref>, which illustrates a cross-section of second platform blade <b>16</b>, engaging member <b>18</b> is generally in the form of a channel or the like, preferably having a U-shape, curved shape, or other shape suitable for engaging the incised sternum.

0095Preferably, engaging member <b>18</b> generally has a concave interior profile <b>17</b> for engaging and holding the sternum and a corresponding convex exterior profile <b>19</b> that is relatively smooth so as not to interfere with other surgical instruments, snag sutures or create other such difficulties. The engaging members <b>18</b> are preferably constructed to have sufficient strength to withstand the loads required to spread the sternum yet maintain a suitably low profile to facilitate easy insertion into the access incision and to require as little space within the working incision as possible.

0096It may be desirable to provide engaging members <b>18</b> with features to reduce trauma to the incision site, increase the traction against the sides of the incision, or both. A thin pad or layer of non-slip or atraumatic material (not shown) may be fixed, by way of an adhesive or other suitable fastening technique, to the interior profile <b>17</b> if desired to reduce slippage and trauma to the severed sternum or surrounding tissue. Alternatively, the desired features may be integrally fabricated into engaging members <b>18</b>. For example, when platform blades <b>14</b> and <b>16</b> are injection molded components, traction features such as raised bumps, ribs, indentations, or the like can be molded integral into engaging members <b>18</b>.

0097Referring to <figref idref="DRAWINGS">FIGS. 2–6</figref>, drive <b>12</b> is preferably constructed to force the platform blades apart in generally opposite directions. Any type of drive mechanism which provides the desired separating action of the blades may be suitable. A common, substantially straight-line parting motion may be provided by a ratchet or rack arrangement as is generally known in the art. <figref idref="DRAWINGS">FIG. 3</figref> illustrates a preferred drive <b>12</b> which involves a bar <b>15</b>, moveable housing <b>22</b> and handle assembly <b>24</b> which facilitates movement of moveable housing <b>22</b> relative to bar <b>15</b>. A first end of first blade <b>14</b> may be operably attached to moveable housing <b>22</b> and second blade <b>16</b> to bar <b>15</b>.

0098In a preferred embodiment, bar <b>15</b> is a substantially rigid bar having a stationary or fixed housing <b>21</b> assembled thereto and thus forming bar assembly <b>23</b>. Fixed housing <b>21</b> may be fastened to one end of bar <b>15</b> using one or more mechanical fasteners, an interference fit, suitable adhesive or bonding compounds, welding, or any other suitable fastening technique. A first end of second blade <b>16</b> is preferably operably attached to fixed housing <b>21</b>. As with moveable housing <b>22</b>, fixed housing <b>21</b> may be of any configuration which provides for the structural attachment of first and second platform blades <b>14</b> and <b>16</b>.

0099Bar <b>15</b> preferably includes a number of teeth <b>13</b> evenly spaced along at least a portion of its length. Teeth <b>13</b> may have substantially parallel side portions <b>11</b> and may have radiused tops <b>25</b>. The exterior edges of teeth <b>13</b> may be broken or radiused or have a chamfer <b>26</b> as shown. Handle assembly <b>24</b> preferably includes a means for engaging teeth <b>13</b> so as to drive moveable housing <b>22</b> relative to bar <b>15</b> to any desired position under load where it remains so positioned against the load without need for any applied input or holding force. The means for engaging teeth <b>13</b> could be any suitable gear, ratchet, cog or like mechanism. Bar <b>15</b> may also be adapted and used for receiving an instrument mount, such as those described in detail below.

0100In a preferred embodiment, moveable housing <b>22</b> is driven using one or more drive pins which may successively engage teeth <b>13</b> in a cogging manner. Handle assembly <b>24</b> includes drive handle <b>29</b> connected to first and second cylindrical drive bearings <b>31</b> and <b>32</b>. Drive bearing <b>31</b> preferably has a raised boss <b>34</b> extending from one end to which drive handle <b>29</b> may be pivotally connected by way of pin <b>33</b>. At the opposite end, drive bearing <b>31</b> has first drive pin <b>27</b> and second drive pin <b>28</b> extending therefrom and terminating at second drive bearing <b>32</b>. First and second drive bearings <b>31</b> and <b>32</b> are spaced apart a distance <b>35</b> which is selected to be slightly greater than the thickness <b>38</b> of bar <b>15</b> such that a portion of bar <b>15</b> may be received between first and second drive bearings <b>31</b> and <b>32</b>. The outside diameters of drive bearings <b>31</b> and <b>32</b> are selected so as to fit within guide holes provided in moveable housing <b>22</b>. For example, the outside diameter of second drive bearing <b>32</b> is sized to accurately rotate within guide hole <b>36</b>.

0101Moveable housing <b>22</b> has a bore <b>37</b> extending therethrough for receiving bar <b>15</b>. Bore <b>37</b> generally has a shape corresponding to the dimensions of the cross-section of the portion of the bar <b>15</b> which is to pass through bore <b>36</b>. With handle assembly <b>24</b> properly positioned within the guide holes provided in moveable housing <b>22</b>, it may be assembled to bar <b>15</b> by placing the end of bar <b>15</b> within bore <b>36</b> and turning handle <b>29</b> such that first and second drive pins <b>27</b> and <b>28</b> become engaged with teeth <b>13</b>. Once assembled in this manner, moveable housing <b>22</b> may be forced one way or the other along the length of bar <b>15</b> by turning handle <b>29</b>, and thus drive bearings <b>31</b> and <b>32</b>, to cause first and second drive pins <b>27</b> and <b>28</b> to progressively engage teeth <b>13</b> along bar <b>15</b>.

0102As mentioned above, first and second platform blades <b>14</b> and <b>16</b> may be removably assembled to moveable housing <b>22</b> and fixed housing <b>21</b>, respectively. Platform blades <b>14</b> and <b>16</b> may be attached in any suitable fashion including, for example, threaded connections or other mating features on the platform blades and housings themselves, ordinary or specialized mechanical fasteners, and cam or latching mechanisms adapted to secure the platform blades to the housings. In a preferred embodiment, both moveable housing <b>22</b> and fixed housing <b>21</b> are constructed with features that engage, secure and support first and second platform blades <b>14</b> and <b>16</b> in an operable position on drive <b>12</b>, thus providing an assembled retractor <b>10</b> which is ready for surgical use.

0103Referring to <figref idref="DRAWINGS">FIGS. 7 and 8</figref>, second platform blade <b>16</b> is shown before and after assembly onto fixed housing <b>21</b>. Preferably, at least one of the platform blade <b>16</b> or the fixed housing <b>21</b> has an extending protuberance, post or like feature which can be receivably engaged by the other of the platform blade or housing. In a preferred embodiment, fixed housing <b>21</b> is preferably constructed to have a latch post <b>42</b> adapted to be received within latch post cavity <b>45</b> provided in platform blade <b>16</b>. Latch post <b>42</b> may have a hole, notch, protuberance, or other feature formed therein which may be engaged in any convenient manner by the platform blade <b>16</b> so that platform blade <b>16</b> becomes releasably locked in place for use.

0104In a preferred embodiment, latch post <b>16</b> has a notch which defines latch surface <b>51</b> and stop surface <b>52</b>. Platform blade <b>16</b> has a latch member <b>48</b>, best seen in FIGS. <b>11</b>A—<b>11</b>A, having a latch body <b>50</b> constructed with surfaces <b>53</b> and <b>54</b> for engaging latch surface <b>51</b> and stop surface <b>52</b> respectively. Generally transverse to latch post cavity <b>45</b>, platform blade <b>16</b> has a latch body cavity <b>56</b> having an opening towards upper surface <b>57</b> of platform blade <b>16</b> for receiving latch body <b>50</b> of latch <b>48</b>.

0105Latch <b>48</b> is preferably constructed to engage and disengage latch post <b>42</b> by manual rotation of latch knob <b>49</b>. Latch body <b>50</b> includes cylindrical portion <b>55</b> which provides for controlled rotation within latch body cavity <b>56</b>. Latch body <b>50</b> may be biased towards the engaged position shown in <figref idref="DRAWINGS">FIG. 8</figref> by way of any suitable spring element. Preferably, latch post <b>42</b> is provided with an angled tip <b>43</b> having a lead-in angle <b>44</b> which allows angled tip <b>43</b> to slide against second engaging surface <b>54</b> as latch post <b>42</b> begins to be received within latch post cavity <b>45</b>. As latch post <b>42</b> is advanced further within latch post cavity <b>45</b>, angled tip <b>43</b> causes latch <b>48</b> to rotate out of the way about cylindrical portion <b>55</b>. Near the end of the advancement of latch post <b>42</b> within latch post cavity <b>45</b>, the angled tip is advanced beyond latch body <b>50</b>, and latch <b>48</b> (which is biased towards an engaged position) rotates into the engaged position with second engaging surface <b>54</b> biased against stop surface <b>52</b>.

0106With latch <b>48</b> and latch body <b>50</b> snapped into the engaged position, any separating force encountered between platform blade <b>16</b> and fixed housing <b>21</b> is resisted by action of first engaging surface <b>53</b> against latch surface <b>51</b>. With this configuration, the reaction force at first engaging surface <b>53</b> is advantageously borne by latch body <b>50</b> primarily in compression. Thus, since the loading is primarily compressive in nature, a high strength material is not required, and latch <b>48</b> can be made from standard engineering polymers, for example, such as polycarbonate.

0107When it is desired to remove platform blade <b>16</b> from drive <b>12</b>, the operator simply turns latch knob <b>49</b>, causing latch body <b>50</b> to be placed in a disengaged position relative to latch post <b>42</b>. With latch <b>48</b> disengaged, latch post <b>42</b> of fixed housing <b>21</b> is free to be removed from latch post cavity <b>45</b> of platform blade <b>16</b>. As is apparent from the Figures, a mirror image of the latch assembly described with reference to platform blade <b>16</b> and fixed housing <b>21</b> is provided to releasably attach platform blade <b>14</b> to moveable housing <b>22</b>.

0108When the retractor assembly is used to gain access to the thoracic cavity, a good deal of force must be generated to create the desired opening. For example, a separating force in excess of 100 pounds may be required to be generated at each engaging member <b>18</b> to achieve the desired separation of a particular sternum. Such loads must be carried by the engaging members and transmitted to drive <b>12</b> by way of platform blades <b>14</b> and <b>16</b>. Since platform blades are preferably made from a suitable engineering polymer (for example, a glass filled thermoplastic polyurethane resin), it may be desirable to provide a reinforcing member for each of platform blades <b>14</b> and <b>16</b> to ensure that platform blades <b>14</b> and <b>16</b> will not break or otherwise rendered inoperable as a result of the loads encountered during use.

0109Although the reinforcing members may be a permanent or removable members within the platform blades themselves, the reinforcing members are preferably one or more substantially rigid members extending from each of the fixed housing <b>21</b> and the moveable housing <b>22</b>. In a preferred embodiment, fixed and moveable housings <b>21</b> and <b>22</b> have a pin extending therefrom which may be received within a mating cavity within first and second platform blades <b>14</b> and <b>16</b>. The pin operates to spread the load developed in the mechanism over a larger internal area within the platform blades <b>14</b> and <b>16</b> and reduces the effective beam length of unreinforced platform blade material subjected to the operating loads. The pin may be straight pin <b>40</b>′ illustrated in <figref idref="DRAWINGS">FIG. 3</figref>. More preferably, fixed and moveable housings <b>21</b> and <b>22</b> have tapered pins <b>40</b> and platform blades <b>14</b> and <b>16</b> have mating tapered cavities <b>41</b> for receiving tapered pins <b>40</b>. The tapered construction tends to allow the user to easily align pin <b>40</b> with cavity <b>41</b> and allows the pins <b>40</b> to fit relatively snugly within cavities <b>41</b> without significant binding during insertion that could otherwise occur between elongate pins and mating cavities which are designed to be very close fitting.

0110To provide sufficient load bearing reinforcement, the reinforcing pins <b>40</b> are preferably constructed of a substantially rigid material, such as steel, and are preferably at least about 0.75 inches long, more preferably at least about 1.125 inches long, and most preferably between about 1.25 inches to about 2.25 inches long. In a preferred embodiment, reinforcing pins <b>40</b> are made from AISI 420 stainless steel having a length of about 1.5 inches, an outside diameter near the housing of about 0.25 inches, and a 2 degree taper angle decreasing towards the free end of the reinforcing pins <b>40</b>.

0111In the preferred embodiments just discussed, platform blade <b>16</b> can be removed from drive <b>12</b> with a substantially straight-line relative motion as indicated by arrow <b>46</b>. This engagement action not only provides for simple and intuitive assembly in the operating room, but also represents a significant safety feature. Under certain rare circumstances, for example where the drive through neglect or misuse has become sufficiently damaged during use that it is unable to close and disengage from the sternum, an extremely dangerous situation can be created for the patient. In such exigent circumstances, the configuration described above may allow the drive to be separated from the in situ platform blades by releasing the latches and applying a sufficient amount of force in the direction indicated by arrow <b>46</b>. Once the drive has been removed, the detached platform blades may be easily removed from the patient.

0112In addition to engaging members <b>18</b>, detachable platform blades <b>14</b> and <b>16</b> may incorporate a wide variety of additional features which enhance the performance of the retractor system. For example, one or both of platform blades <b>14</b> and <b>16</b> may have mounting features to which various instruments used during the procedure can be secured. In the case where a stabilizer is to be secured to a retractor for operating on a beating heart, it is critical to minimize or substantially eliminate the amount of flex and motion attributable to each component and each connection between each component, from the component engaging the beating heart to the component which provides the sternal attachment. To this end, the engaging features <b>18</b> which engage the sternum are preferably part of a unitary platform blade structure which also includes mounting features to which a stabilizer and other instruments can be mounted. Since the mounting features and the sternal engaging features are part of the same component, and therefore there is no mechanical connection between the two, the stability of an attached instrument against the forces of a beating heart is greatly improved.

0113In a preferred embodiment, each of first and second platform blades <b>14</b> and <b>16</b> include mount features in the form of rails. The rails allow one or more instruments to be positioned at any desired location along the operable length of the rail. Preferably, the rails are oriented in a direction generally perpendicular to the direction of separation, in this case perpendicular to bar <b>15</b>. The rails may be a recessed feature within the body of platform blades <b>14</b> and <b>16</b>. More preferably, the mounting rails extend upwardly from the body of platform blades <b>14</b> and <b>16</b>.

0114Referring to <figref idref="DRAWINGS">FIGS. 7–9</figref>, right platform blade <b>16</b> has rail <b>60</b> extending over at least a portion of the length of platform blade <b>16</b>. Rail <b>60</b> may have a top portion and a bottom portion having a narrowed region adjacent said top portion. In one embodiment, Rail <b>60</b> preferably has a T-shaped cross-section. The T-shaped configuration has a top portion <b>61</b> and a narrowed portion <b>62</b>, thus forming mounting tabs <b>63</b> and <b>64</b> which can be gripped by a number of appropriately constructed mounts.

0115The rail may be straight, curved, or a combination of straight and curved portions. Preferably, at least a portion of the T-shaped rail is curved in a manner which more closely follows the profile of the access or incision site (as seen, for example, see <figref idref="DRAWINGS">FIG. 45</figref>). In a curved rail configuration, instruments extending perpendicular to a generally central axis <b>67</b> of rail <b>60</b> will naturally point more towards a central area between the platform blades <b>14</b> and <b>16</b>, and thus may require less positional adjustment or manipulation from their normal, natural or beginning position. In addition, all or a portion of top portion <b>61</b>, and more specifically mounting tabs <b>63</b> and <b>64</b>, may be tilted or angled inwardly at an angle <b>65</b> as shown.

0116Platform blade <b>16</b> may be also be provided with a number of suture holders or stays which can be used to organize or capture various sutures used in the course of a particular surgery. Since certain sutures are placed near the beginning of a CABG procedure, such as pericardial sutures used to position the heart, the placement of the suture stays in a manner which does not interfere with subsequent procedures and instruments is an important aspect of the present invention. Preferably, the suture stays are positioned such that placing and manipulating the sutures or the various instruments and instrument mounts employed during surgery can be accomplished without interfering with each other. Preferably, the location of the suture stays position the sutures below the level of the mounting tab <b>63</b> and <b>64</b> so that a mating instrument mount may traverse the entire operable length of rail <b>60</b> without interfering with the sutures.

0117Rail <b>60</b> may have one or more grooves, channels, slots or passageways for receiving a suture. In addition, a suture lock may be provided in the rail or elsewhere on platform blade <b>16</b> so that the suture may be fixed in place. To accommodate the use of pericardial sutures, which are often subjected to a significant amount of tension when used to position the heart, the suture locks must be adapted to hold the suture material even while under a significant amount of tensile loading.

0118In a preferred arrangement for organizing and locking sutures, and in particular tensioned pericardial sutures, rail <b>60</b> has at least one open slot or passageway formed therein for receiving the free end portions of a surgically placed suture. The passageways preferably extend across rail <b>60</b> and have a depth which allows the suture to lay at an elevation sufficiently below mounting tabs <b>63</b> and <b>64</b> so as not to interfere with an instrument mount sliding along rail <b>60</b>. In a preferred embodiment the passageways extend through at least a portion of narrowed portion <b>62</b>. Thus, the height <b>66</b> of narrowed portion <b>62</b> may be selected not only to provide sufficient space for a desired instrument mount to attach, but also to ensure that mounting tabs <b>63</b> and <b>64</b> are sufficiently raised above the surrounding features of platform blade <b>16</b> so that an instrument mount may be positioned and repositioned along rail <b>60</b> without disturbing or disrupting the sutures within the various passageways.

0119The passageways may be a single channel for receiving both free ends of a surgically placed suture or each end may have a separate channel. In a preferred embodiment, rail <b>60</b> has a number of bifurcated channels <b>70</b> at predetermined intervals along its length. Referring to <figref idref="DRAWINGS">FIG. 10</figref>, bifurcated channel <b>70</b> has a single entrance channel <b>71</b> which bifurcates into first and second exit channels <b>72</b> and <b>73</b>. Entrance channel <b>71</b> and either one of exit channel <b>72</b> or <b>73</b> can be used in the same manner as a single channel, with both free ends <b>76</b> and <b>77</b> being routed together. Alternatively, both suture ends may be received within entrance channel <b>71</b> and then separated, one end within exit channel <b>72</b> and one end within exit channel <b>73</b>.

0120A means for clamping the suture against movement within the suture channels may be provided on any of entrance channel <b>71</b> or exit channels <b>72</b> or <b>73</b>. Preferably, suture locks are provided on each exit channel <b>72</b> and <b>73</b>. This allows the surgeon to positively identify and unlock a desired suture end for further tension adjustments or other manipulation without unlocking or loosening the other end of the suture. In addition, placing each suture end <b>76</b> and <b>77</b> in separate exit channels <b>72</b> and <b>73</b>, each with a dedicated suture lock, increases the maximum amount of tension that can be applied to a given suture. Exit channels <b>72</b> and <b>73</b> may have recesses <b>74</b> and <b>75</b>, respectively associated therewith for receiving a suture lock adapted to secure the suture material within the channels.

0121A preferred suture lock <b>80</b> is illustrated in <figref idref="DRAWINGS">FIGS. 10 and 12</figref>. Suture lock <b>80</b> has a relatively rigid body <b>83</b> having a fixed or pivot end <b>81</b> which allows body <b>83</b> to pivot within the mating profile of recess <b>74</b> or <b>75</b>. Pivoting the body <b>83</b> about pivot end <b>81</b> selectively engages and disengages free end <b>84</b> against the wall <b>78</b> of exit channel <b>72</b> or <b>73</b>. Alternatively, suture lock <b>80</b> may be made from a more flexible material which, by nature of the elastic properties of the material, tends to flex about its fixed end instead of rotate. In a preferred embodiment, fixed or pivot end <b>81</b> is substantially cylindrical and recesses <b>74</b> and <b>75</b> have mating cylindrical surfaces.

0122Preferably, the suture lock is angled relative to the wall <b>78</b> so that it is self-locking in one direction. That is, the suture ends <b>76</b> or <b>77</b> (or both) operate on the free end <b>84</b> in such a way as to force it towards wall <b>78</b>, and thus against the suture material, in proportion to the tension, T encountered by suture ends <b>76</b> or <b>77</b>. Thus, within practical limits, the higher the tension the harder free end <b>84</b> will press or bite against the sutures placed therein. Conversely, when the suture ends are pulled in the direction indicated by arrow <b>79</b>, the suture forces tend to pivot body <b>83</b> about pivot <b>81</b> such that free end <b>84</b> is rotated away from wall <b>84</b> allowing the suture to move relatively freely. Preferably, angle <b>79</b> between body <b>83</b> and wall <b>78</b> is nominally about 1 degree to about 30 degrees, more preferably about 5 degrees to about 15 degrees, most preferably about 10 degrees. Of course, angle <b>79</b> is greater as body <b>83</b> pivots to accept a suture placed within the suture channel.

0123Suture lock <b>80</b> may be biased towards the locked position, preferably using a small spring between the suture lock and the recess <b>75</b>. In a preferred embodiment, a piece of resilient closed cell foam <b>89</b> is fixed to body <b>83</b> to provide the desired biasing effect. Free end <b>84</b> may optionally have a number of teeth or ridges <b>82</b> to ensure acceptable traction against the suture material.

0124Platform blades <b>14</b> and <b>16</b> may also be provided with soft tissue retainers to help control and retain the incised tissue and fat in the immediate vicinity of the blades. Referring to <figref idref="DRAWINGS">FIGS. 8 and 9</figref>, platform blade <b>16</b> includes integrally attached tissue retainer <b>85</b>. Tissue retainer <b>85</b> is generally at a small distance <b>88</b> above the top of the engaging members <b>18</b>. Tissue retainer <b>85</b> may be made from a flexible material, such as an elastomer, preferably a polyurethane elastomer having a durometer in the range of about 45 to about 75 Shore D, more preferably about 55 Shore D. In a preferred embodiment tissue retainer <b>85</b> is injection molded over the platform blade to form a permanent and inseparable assembly. Tissue retainer <b>85</b> may have a raised outer lip <b>86</b> and optionally having a plurality of slots <b>87</b> formed therein to receive and organize any loose suture ends. Tissue retainer <b>85</b> ensures that the tissue surrounding the access incision does not interfere with the operation of rail <b>60</b> or the suture holders and also provides a convenient location for attaching surgical drapes of the like without interfering with the operation of the retractor assembly.

0125Although some of the features of the present invention have been described, for illustration only, with respect to only one of the platform blades <b>14</b> and <b>16</b>, it should be apparent that both platform blades <b>14</b> and <b>16</b> may have similar or identical features. Although not necessarily so, first platform blade <b>14</b> and second platform blade <b>16</b> are preferably substantially mirror images of each other.

0126The retractor assembly just described, provides a simplified drive mechanism for use in conjunction with multi-featured platform blades. In addition, a number of different platform blades may be provided for use with a single drive, for instance, tailored to different sized anatomy or the specifics of different surgical procedures. Thus, a number of platform blade configurations can be provided to an operating room and, based upon pertinent prevailing clinical factors, the proper configuration can be selected, mounted to drive <b>12</b>, and used as described above to provide access to a desired location. Also, with the modular configuration new features and advancements can be rapidly incorporated into the platform blades and immediately introduced for use with existing simplified drives already in place in the operating rooms.

0127The platform blades themselves represent a surgical platform that allows instruments to be mounted and stabilized in virtually any position, even over already placed and secured sutures from the surgical site accessed by the retractor assembly. Described below are preferred instrument mounts for use in conjunction with rail <b>60</b> to secure a beating heart stabilizer or other instruments such as heart positioners, saline or medical air blowers, suction devices, surgical clamps, or vessel occluders.

0128The Instrument Mount

0129Referring to <figref idref="DRAWINGS">FIG. 13</figref>, a preferred instrument mount assembly <b>20</b> is shown for mounting an instrument, such as stabilizer assembly <b>30</b>, to an instrument mounting rail such as described above with respect to rail <b>60</b> of platform blades <b>14</b> and <b>16</b>. Mount assembly <b>20</b> includes mount base <b>115</b> having features to secure mount assembly <b>20</b> at a desired position on an appropriately configured mating rail or other suitable structure and includes a shaft locking mechanism for controlling and securing an instrument shaft in a desired position and orientation.

0130One important aspect of instrument mount assembly <b>20</b> is to provide the necessary degrees of freedom to allow the instrument to be easily maneuvered to whatever position may be required by a particular procedure. As discussed above, an additional aspect with respect to stabilizing the beating heart is to eliminate or minimize the flex or motion attributable to the various components and connections of instrument mount assembly <b>20</b>. As will be discussed in more detail below, instrument mount assembly <b>20</b> is uniquely suited for use in stabilizing the beating heart because it allows sufficient degrees of freedom to easily manipulate the position of an instrument secured thereto, allows the degrees of freedom to be frozen or locked in place and, once locked in place, does not significantly flex or allow movement at any of the mechanical joints or connections.

0131Instrument mount assembly <b>20</b> provides a number of different controllable joints that, when in a released condition, allows motion in one or more predetermined directions or about one or more degrees of freedom. Although instrument mount assembly <b>20</b> may be used to secure any mounting shaft configuration from straight or curved substantially rigid shafts to multi-link or segmented ball and socket type shafts which are relatively flexible until themselves locked in some manner at each joint along the shaft length, it is most advantageously constructed to provide the joints or connections required to position an instrument having a straight or curved rigid shaft.

0132In a preferred embodiment, instrument mount assembly <b>20</b> has three releasable joints or connections for controlling the location and position of the instrument mount assembly and instrument attached thereto. The mount base may be positioned at a desired location along an appropriate rail and secured by rail grips <b>114</b> and <b>116</b>. The position and orientation of the instrument is then determined by ball joint (or ball and socket joint) <b>112</b> between mount base <b>125</b> and mount body <b>110</b>, a rotational joint <b>157</b> between mount body <b>110</b> and shaft hub assembly <b>160</b>, and a shaft clamping mechanism within shaft hub assembly <b>160</b> which may allow translation, rotation, or both of shaft <b>3</b> relative to shaft hub assembly <b>160</b>.

0133Ball joint <b>112</b> is preferably of the ball and socket type having <b>3</b> rotational degrees of freedom. Rotational joint <b>157</b> allows rotation of shaft hub assembly <b>160</b> about axis <b>121</b> as indicated by arrow <b>113</b>. The shaft clamping mechanism allows translation of instrument shaft <b>3</b> as indicated by arrows <b>111</b> as well as rotation about the shaft itself as indicated by arrow <b>117</b>. As will be discussed later, a further ball-joint type connection <b>201</b> may be employed between shaft <b>3</b> and the particular end-effector of the instrument.

0134Instrument mount assembly <b>20</b>, having the particular joints and connections identified above, allows all the required areas of the heart to be conveniently and intuitively accessed by a stabilizer connected to one end of a substantially rigid shaft. Certainly, instrument mount assembly <b>20</b> could be provided with more or less degrees of freedom for maneuvering a particular instrument. For example, to add additional degrees of freedom rotational joint <b>157</b> could be replaced with a ball joint and to eliminate degrees of freedom shaft <b>3</b> could be keyed within shaft hub assembly <b>160</b> or ball joint <b>112</b> could be replaced with a rotation only joint. However, it should be noted that excessive degrees of freedom may tend to make instrument adjustment increasingly difficult and cumbersome to control while too few degrees of freedom may not allow the instrument to be easily placed in the desired position or orientation.

0135In one embodiment, the various joints and connections are locked into a desired position by way of a series of knobs. The degrees freedom provided by ball joint <b>112</b> is locked by activation of top mount knob <b>120</b>. Both rotational joint <b>157</b> and the shaft clamping mechanism of shaft hub assembly <b>160</b> is locked in place by the activation of side mount knob <b>118</b>. Base <b>125</b> is locked in position on the rail by activation of mount lever <b>122</b>. Ball joint <b>201</b>, as will be discussed in greater detail below, may be locked in position by activation of knob <b>504</b>. This particular sequence of knobs used to lock down the degrees of freedom associated with instrument mount assembly <b>20</b> tends to allow the user greater precision in positioning the instrument because degrees of freedom unnecessary to a particular desired maneuver of the instrument can be locked down. Most commonly, mount body <b>110</b> is placed at a desired angle or orientation and then fixed in place by locking ball joint <b>112</b>, leaving final adjustment to take place using rotational joint <b>157</b> and the shaft movement allowed by the shaft clamping mechanism of shaft hub assembly <b>160</b>.

0136<figref idref="DRAWINGS">FIGS. 14–20</figref> show in greater detail the various mechanisms which lock and release the joints or connections associated with instrument mount assembly <b>20</b>. <figref idref="DRAWINGS">FIG. 14</figref> shows an exploded assembly illustration of instrument mount assembly <b>20</b>. Instrument mount assembly <b>20</b>, and more specifically mount base <b>125</b> to which all the other components are ultimately secured, is preferably constructed to engage and lock in position on a rail or other suitable feature.

0137Preferably, instrument mount assembly <b>20</b> has a fixed rail grip <b>114</b> adapted to engage mounting tab <b>64</b> of rail <b>60</b> and a moveable rail grip <b>116</b> adapted to engage mounting tab <b>63</b> or rail <b>60</b>. Rail grips <b>114</b> and <b>116</b> may generally have hook-like features for gripping mounting tabs <b>63</b> and <b>64</b>. Rail grip <b>114</b> is part of mount base <b>125</b> and moveable rail grip <b>116</b> is part of articulating hinge member <b>115</b>, which is pivotally attached to mount base <b>125</b> by way of hinge pins <b>123</b> and <b>124</b>, or other suitable fastener. Articulation of hinge member <b>115</b> and rail grip <b>116</b> in clamping manner towards rail grip <b>114</b> on mount base <b>125</b> effectively clamps mount base <b>125</b> onto rail <b>60</b> at mounting tabs <b>63</b> and <b>64</b>.

0138Hinge member <b>115</b> may be articulated using any suitable mechanism capable of pivoting hinge member <b>115</b> to a closed position and holding it there. In a preferred embodiment, best illustrated in <figref idref="DRAWINGS">FIGS. 15A–17</figref>, hinge member <b>115</b> includes follower surface <b>155</b> which may be acted upon by any suitable cam device to drive hinge member <b>115</b> about hinge pins <b>123</b> and <b>124</b>, thus urging rail grip <b>116</b> towards rail grip <b>114</b>.

0139In a preferred embodiment, hinge member <b>115</b> is articulated by action of cam <b>145</b> having cam surface <b>152</b> which acts upon follower surface <b>155</b>. Cam <b>145</b> has a center, C about which cam <b>145</b> rotates. Preferably, cam <b>145</b> has bore <b>127</b>, having its central axis coincident with center, C. Mount base <b>125</b> may have a cam guide <b>153</b> around which bore <b>127</b> rides for smooth rotation of cam <b>45</b> about center, C. Cam surface <b>152</b> has a varying radius, illustrated by exemplar radial lines R₁, R₂, R₃, R₄, and R₅. Thus as cam surface <b>152</b> is rotated past follower surface <b>155</b>, from example from R<b>1</b> to R<b>2</b>, it pushes the follower surface a greater distance away from center, C, thus causing hinge member <b>115</b> to pivot about hinge pins <b>123</b> and <b>124</b>, thus causing rail grip <b>116</b> to move closer to rail grip <b>114</b>.

0140The varying radius of cam surface <b>152</b> may be configured to place hinge member <b>115</b>, and thus rail grip <b>116</b> in a variety of positions. A first portion of cam surface <b>152</b> may be configured such that follower surface <b>155</b> biased against cam surface <b>152</b> is placed in an position characterized in that rail grip <b>116</b> is sufficiently spaced apart relative to rail grip <b>114</b> to allow assembly onto a rail or other structure. A second portion of cam surface <b>152</b> has an increasing radius such that rotation of cam <b>145</b> moves rail grip <b>116</b> towards rail grip <b>114</b> to an intermediate position. In the intermediate position, rail grip <b>116</b> has been moved close enough to rail grip <b>114</b> so that it becomes captured on a rail but remains loose enough to slide along the rail. A third portion of cam surface <b>152</b> has an increasing radius such that the rotation of cam <b>145</b> moves rail grip <b>116</b> further towards rail grip <b>114</b> to a completely locked position wherein relative motion between rail grips <b>114</b>, <b>116</b> and the rail is essentially no longer possible.

0141Cam <b>145</b> is generally provided with a handle or lever <b>122</b> to allow the user to easily turn cam <b>145</b> relative to mount base <b>125</b>. Cam <b>145</b> may be captured onto mount base <b>125</b> by operation of retaining hook <b>150</b> on cam <b>145</b> which rides within exterior groove <b>151</b> on mount base <b>125</b> on one side, and projection <b>154</b> which is engaged below undercut <b>156</b> generally opposite to retaining hook <b>150</b>. Projection <b>154</b> also serves to work against undercut <b>156</b> to return hinge member <b>115</b> to the open position as cam <b>145</b> is rotated in the opposite (open) direction. Hinge member <b>115</b> preferably has first and second end stops <b>158</b> and <b>159</b> between which the motion of projection <b>154</b> (and thus the rotation of cam <b>145</b>) is limited. Cam <b>145</b> may also have a protective extended portion or cover <b>163</b> which shields the area of groove <b>151</b> when assembled over mount base <b>125</b>.

0142The assembly of cam <b>145</b> and hinge member <b>115</b> to mount base <b>125</b> is illustrated in <figref idref="DRAWINGS">FIGS. 15A and 15B</figref>. Cam <b>145</b> is placed in position relative to hinge member <b>115</b> with projection <b>154</b> in place below undercut <b>156</b>. In roughly that position, cam <b>145</b> and hinge member <b>115</b> are brought over mount base <b>125</b> until bore <b>127</b> is properly seated over cam guide <b>153</b> and retaining hook <b>150</b> is positioned within groove <b>151</b>. Pins <b>123</b> and <b>124</b> are then pressed in place through holes provided in both mount base <b>125</b> and hinge member <b>115</b>.

0143Ball joint <b>112</b> is generally created between ball <b>129</b> provided at the top of mount base <b>125</b> and a socket or mating cavity within mount body <b>110</b> adapted to receive at least a portion of ball <b>129</b>. Preferably ball <b>129</b> includes a generally spherical portion, although other curved shapes providing the desired degrees of freedom may also be suitable. Base post <b>130</b> extends vertically upward through bore <b>126</b> of mount base <b>125</b> and vertical passageway <b>128</b> of mount body <b>110</b> until enlarged end portion <b>130</b> become biased against mount base <b>125</b>. Top mount knob <b>120</b> may then be threaded onto threaded shaft <b>132</b> whereby mount base <b>125</b> and mount body <b>110</b>, with ball <b>129</b> received within mount base <b>125</b>, becomes captured between top mount knob <b>120</b> and enlarged end portion <b>130</b>. Continued tightening of top mount knob <b>120</b> over threaded shaft <b>132</b> forces ball <b>129</b> harder against mount body <b>110</b> until the friction between mating surfaces on ball <b>129</b> and mount body <b>110</b> become so great as to effectively resist any relative movement, thus locking ball joint <b>112</b>.

0144The assembly of rotational joint <b>157</b> and shaft hub assembly <b>160</b> are shown in <figref idref="DRAWINGS">FIG. 19</figref>. Rotational joint <b>157</b> is in the form of a conical clutch formed between frustoconical surface <b>138</b> of clutch member <b>135</b> and mating frustoconical surface <b>139</b> in mount body <b>110</b>. Shaft hub assembly <b>160</b> is generally formed as upper and lower shaft locks <b>136</b> and <b>137</b> are advanced over shaft grip <b>140</b> and against instrument shaft <b>3</b> which is positioned between shaft locks <b>136</b> and <b>137</b> and outer shaft guide <b>144</b>. As clutch member <b>135</b> is received over the outside diameter of grip housing <b>141</b> of shaft grip <b>140</b> tang <b>164</b> becomes engaged between upper shaft lock <b>136</b> and lower shaft lock <b>137</b> thereby preventing relative rotation between clutch member <b>135</b> and shaft grip <b>140</b>.

0145Side mount knob <b>118</b> having threaded shaft <b>119</b> extends through mount body <b>110</b> (and consequently through transverse bore <b>131</b> in central portion <b>167</b> of base post <b>130</b>), clutch member <b>135</b> and into interior threads <b>142</b> within grip housing <b>141</b> of shaft grip <b>140</b>. Tightening of side mount knob <b>118</b> clamps the assembly together. Thus, translation and rotation of instrument shaft <b>3</b> is prevented as shaft grip <b>140</b> and clutch member <b>135</b> are forced together to clamp or trap instrument shaft <b>3</b> between shaft locks <b>136</b> and <b>137</b> and outer shaft guide <b>144</b>. Also, relative rotation between frustoconical surface <b>138</b> of clutch member <b>135</b> and mating frustoconical surface <b>139</b> in mount body <b>110</b> is prevented as clutch member <b>135</b> is forced against mount body <b>110</b>. One or both of frustoconical surface <b>138</b> and mating frustoconical surface <b>139</b> may include a number of teeth, ridges, or other features to prevent rotation when clutch member <b>135</b> is forced against mount body <b>110</b>.

0146So that the shaft does not become too loose as side mount knob <b>118</b> is loosened, a minimum amount of friction between instrument shaft <b>3</b> and the clamping surfaces <b>146</b> of outer shaft guide <b>144</b> is preferably maintained by providing a biasing load against shaft <b>3</b>. Referring to <figref idref="DRAWINGS">FIG. 20</figref>, shaft biasing member <b>147</b> is provided within shaft grip <b>140</b> to maintains a biasing load against shaft <b>3</b>. Shaft biasing member <b>147</b> has a first portion <b>148</b> which slides within counterbore <b>143</b> in shaft grip <b>140</b>. Shaft biasing member <b>147</b> may optionally have a second portion <b>149</b> having external dimensions sized to be received within the inside diameter of compression spring <b>133</b>. Compression spring <b>133</b> urges end <b>134</b> of shaft biasing member <b>147</b> against shaft <b>3</b> to force shaft <b>3</b> against clamping surfaces <b>146</b>. The amount of force is selected to allow instrument shaft <b>3</b> to be easily positioned by hand but would generally not allow instrument shaft <b>3</b> to slide relative to shaft grip <b>140</b> under only its own weight.

0147Referring to <figref idref="DRAWINGS">FIG. 21</figref> a preferred instrument mount assembly <b>20</b> is shown fixed to a preferred platform blade <b>16</b> having rail <b>60</b>. As discussed above, rail <b>60</b> has mounting tabs <b>63</b> and <b>64</b> over which rail grips <b>114</b> and <b>116</b> may be secured. Instrument mount assembly <b>20</b> can be positioned, maneuvered, and removed virtually anywhere along rail <b>60</b> without disturbing suture <b>166</b> locked in place by free end <b>84</b> of suture lock <b>80</b> below the operating features of instrument mount assembly <b>20</b> within any one of the suture channels provided in platform blade <b>16</b>. In addition, rail <b>60</b> is placed in close proximity to engaging member <b>18</b> and thus close to the surgical opening into the patient providing a more direct access to the heart by an instrument mounted to instrument mount assembly <b>20</b>. Since the rail <b>60</b> moves in unison with platform blade <b>16</b>, this relationship between rail <b>60</b> and engaging member <b>18</b> is maintained no matter how much or how little platform blades <b>14</b> and <b>16</b> have been spread to create the desired surgical opening. <figref idref="DRAWINGS">FIGS. 22A–32</figref> illustrate a preferred embodiment of an alternative instrument mount assembly <b>220</b>. Preferably, the degrees of freedom available for maneuvering instrument mount <b>220</b> is substantially the same as that of instrument mount assembly <b>20</b>. Instrument mount assembly <b>220</b> preferably has ball joint <b>112</b> between mount base <b>221</b> and mount body <b>222</b>, a rotational joint <b>157</b> between mount body <b>222</b>, and a shaft hub assembly <b>227</b> which allows rotation and translation of an instrument shaft held between shaft grip <b>226</b> and clutch member <b>226</b> of shaft hub assembly <b>227</b>. Instrument mount assembly <b>220</b>, however, has a different mechanism for controlling or locking the various joints and connections and may also provide a means for releasing and removing the shaft from the bulk of the remainder of instrument mount assembly <b>220</b>.

0148As just mentioned, the joints and connections themselves are quite similar between instrument mount assemblies <b>20</b> and <b>220</b>. As before, ball joint <b>112</b> is a ball and socket configuration created between generally spherical ball <b>224</b> provided at the top of mount base <b>221</b> and a mating cavity within mount body <b>222</b> adapted to receive and slide against at least a portion of ball <b>224</b>. Rotational joint <b>157</b> may be in the form of a conical clutch formed between frustoconical surface <b>243</b> of clutch member <b>225</b> and mating frustoconical surface <b>244</b> in mount body <b>222</b>. An instrument shaft may be clamped in place within shaft hub assembly <b>227</b> by forcing together shaft grip <b>226</b> and clutch member <b>225</b> thus closing clamp surface <b>239</b> of outer shaft guide <b>233</b> towards V-shaped channels <b>273</b> on shaft locks <b>231</b> and <b>232</b>.

0149Instead of locking the joints and connections by way of multiple knobs as described above with respect to instrument mount assembly <b>20</b>, instrument mount assembly <b>220</b> preferably uses a mechanism which releases each of ball joint <b>112</b>, rotational joint <b>157</b>, and the shaft clamping mechanism of shaft hub assembly <b>227</b> by activation of a single knob, lever, or other suitable manual interface. Generally speaking, this is accomplished by utilizing the clamping motion required to lock one or more of the joints or connections along a first axis to also lock the remainder of the joints or connections along remaining axes.

0150In a preferred embodiment, ball <b>224</b> of mount base <b>221</b> is locked in place relative to housing <b>222</b> by operation of base post <b>230</b>. Base post <b>230</b> is assembled through mount base <b>221</b> and mount body <b>222</b> from the bottom until bottom flange <b>259</b> (see <figref idref="DRAWINGS">FIG. 27</figref>) is resisted against mount base <b>221</b>. At the top of base post <b>230</b> is upper link portion <b>256</b> having pivot hole <b>257</b>. Cam <b>235</b> is attached through pivot hole <b>257</b> at off-center link pivot <b>238</b> using a pin or other suitable fastener and is supported by contact surface <b>236</b> associated with mount body <b>222</b>. Contact surface <b>236</b> may be an integral feature of mount body <b>222</b> or may be in a separate mount body cover <b>254</b> which may be selected to have superior wear characteristics.

0151With cam <b>235</b> in a closed position, as shown in <figref idref="DRAWINGS">FIG. 24</figref>, link pivot <b>238</b> is drawn to its maximum distance <b>251</b> (or slightly less than the maximum if the cam is constructed to rotate over center) from contact surface <b>236</b> thus increasing the clamping force between mount body <b>222</b> and ball <b>224</b> as the assembly is clamped between cam <b>235</b> on the top and bottom flange <b>259</b> on the bottom. With cam <b>235</b> in the closed position, ball joint <b>112</b> is effectively locked.

0152By rotating cam <b>235</b>, by way of handle <b>237</b>, to an open position as illustrated in <figref idref="DRAWINGS">FIG. 25</figref>, link pivot <b>238</b> is withdrawn to a position closer to contact surface <b>236</b> at a distance <b>252</b>, thus reducing or relaxing the clamping forces between mount body <b>222</b> and ball <b>224</b> of mount base <b>221</b>. With cam <b>235</b> in the open position, the friction at ball <b>224</b> is reduced to a level that allows the user to easily manipulate mount body <b>222</b> relative to mount base <b>221</b>.

0153Mount base <b>221</b> may have an insert <b>253</b> secured in the bottom thereof against which bottom flange <b>259</b> is caused to seat as upper link portion <b>256</b> is drawn upwards by operation of cam <b>235</b>. Preferably, insert <b>253</b> includes recess <b>255</b> for receiving compression spring <b>248</b> captured about base post <b>230</b>. Compression spring <b>248</b> operates between insert <b>253</b>, and thus mount base <b>221</b>, and bottom flange <b>259</b> to bias base post <b>230</b> towards the unlocked position.

0154That same motion of base post <b>230</b>, created by operation of cam <b>235</b>, is preferably also used to lock both rotational joint <b>157</b> and the instrument shaft clamping mechanism of shaft hub assembly <b>227</b>. Instead of using a threaded shaft to clamp instrument mount assembly along this axis as did the previous embodiment, instrument mount assembly <b>220</b> preferably utilizes tie pin <b>240</b> which is driven in the direction of arrow <b>245</b> causing shaft grip <b>226</b> and clutch member <b>225</b> to be forced together to clamp an instrument shaft placed therein and also causing frustoconical surface <b>243</b> of clutch member <b>225</b> to forced against frustoconical surface <b>244</b> in mount body <b>222</b>.

0155Tie pin <b>240</b> preferably has a generally cylindrical back portion <b>261</b> and a front portion which is connected in some manner to shaft grip <b>226</b>. Preferably, the front portion includes forward extending first and second flexible prongs <b>262</b> and <b>263</b>. Cylindrical back portion <b>261</b> is slidably received within blind hole <b>272</b> of release button <b>242</b> and is preferably biased in the unlocked direction indicated by arrow <b>270</b> by compression spring <b>247</b> positioned within blind hole <b>272</b> behind tie pin <b>240</b>.

0156Tie pin <b>240</b> is preferably driven in the direction of arrow <b>245</b> by the movement of base post <b>230</b> which is assembled in the space between first and second prongs <b>262</b> and <b>263</b> of tie pin <b>240</b>. Preferably, base post <b>230</b> has an angled cam or ramp <b>258</b> that engages back wall <b>269</b> at the base of first and second prongs <b>262</b> and <b>263</b>. As base post <b>230</b> is drawn upwards in the direction of arrow <b>271</b> by cam <b>235</b> from the open position of <figref idref="DRAWINGS">FIG. 25</figref> to the closed position of <figref idref="DRAWINGS">FIG. 24</figref>, ramp <b>258</b> progressively forces back wall <b>269</b>, and thus tie pin <b>240</b>, in the direction of indicated by arrow <b>245</b>.

0157Tie pin <b>240</b>, connected at its front end to shaft grip <b>226</b>, locks an instrument shaft in place and locks rotational joint <b>157</b> in the same manner as did threaded shaft <b>119</b> of instrument mount assembly <b>20</b>. In sum, tie pin <b>240</b> urges shaft grip <b>226</b> towards clutch member <b>225</b> and mount body <b>222</b>. The movement of shaft grip <b>226</b>, having tang <b>236</b> engaged between upper and lower shaft locks <b>231</b> and <b>232</b> of clutch member <b>225</b>, closes together in a clamping fashion surfaces <b>239</b> on shaft grip <b>226</b> and V-shaped channels <b>273</b> on clutch member <b>225</b>. At the same time, shaft grip <b>226</b> pushes against clutch member <b>225</b> to force frustoconical surface <b>243</b> against mating frustoconical surface <b>244</b> with sufficient force to frictionally lock the surfaces together, thus preventing relative motion therebetween.

0158The operation of cam <b>235</b> has been described as generally moving between an open position, in which the various joints and connections of instrument mount assembly <b>220</b> are free to be easily manipulated about their respective degrees of freedom, and a closed position in which the joints and connections resist any relative movement and are thus effectively locked in position. However, the outer cam profile of cam <b>235</b> operating against contact surface <b>236</b> may be given a profile that has one or more intermediate positions such that link pivot <b>238</b> is placed at an intermediate distance from contact surface <b>236</b>. In an intermediate position, the joints and connections may be in a stiffened or partially locked state which allows some positional and orientational manipulation with somewhat higher operator forces that the completely released condition. In addition, the action of base post <b>230</b> may be such that ball joint <b>112</b> becomes fully locked before tie pin <b>240</b> has completely locked the remaining degrees of freedom. Thus, cam <b>235</b> may have a completely released position where manipulation about all degrees of freedom is easily accomplished, an intermediate position in which only ball joint <b>112</b> is fully locked and the remaining degrees of freedom are unlocked or may be partially locked, and final closed position in which all degrees of freedom are locked.

0159Instrument mount assembly <b>220</b> may optionally be provided with a release mechanism allowing shaft grip <b>226</b>, and thus the instrument shaft slidably assembled therein, to be released from instrument mount assembly <b>220</b> preferably by activation of release button <b>242</b>. This allows instruments associated with instrument mount assembly <b>220</b> to be quickly and conveniently removed and replaced or exchanged.

0160In a preferred embodiment, first and second prongs <b>262</b> and <b>263</b> of tie pin <b>240</b> have first and second projections <b>267</b> and <b>268</b> which releasably attach tie pin <b>240</b> to shaft grip <b>226</b>. Grip housing <b>274</b> of shaft grip <b>226</b> is covered with a sleeve having a deep counterbore <b>278</b> and small through hole <b>279</b>. The depth of counterbore <b>278</b> is longer than the exterior of grip housing <b>274</b> so as to form internal space <b>290</b> (see <figref idref="DRAWINGS">FIG. 25</figref>) when assembled. First and second prongs <b>262</b> and <b>263</b> can be flexed to position projections <b>267</b> and <b>268</b> relatively close together for insertion through hole <b>279</b> where projections <b>267</b> and <b>268</b> can then expand apart locking projections <b>267</b> and <b>268</b> behind surface <b>280</b>.

0161Preferably, projections <b>267</b> and <b>268</b> have lead-ins <b>291</b> and <b>292</b> which urged projections <b>267</b> and <b>268</b> together as they are advanced through hole <b>279</b> so that shaft grip <b>226</b> can simply be aligned with lead-ins <b>292</b> and <b>292</b> and then snapped into place without any further action. Alignment of hole <b>279</b> is generally quite simply accomplished as the cylindrical exterior surface <b>277</b> of sleeve <b>260</b> is slidably received in a substantially coaxial arrangement within center bore <b>219</b> of clutch member <b>225</b>. Clutch member <b>225</b> may optionally have first and second flexures <b>281</b> and <b>282</b> having first and second retaining features <b>283</b> and <b>284</b> so that it may be snapped in place and thereafter retained within mount body <b>222</b>.

0162As mentioned above, shaft grip <b>226</b> may be released from tie pin <b>240</b>. To separate tie pin <b>240</b>, it is necessary to flex first and second prongs <b>262</b> and <b>263</b> together so that projections <b>267</b> and <b>268</b> will again be positioned to fit through hole <b>280</b>. This may be accomplished by providing a raised portion <b>264</b> having a ramp <b>266</b> on tie pin <b>240</b>. A sliding member may be advanced up tie pin <b>240</b> and over ramp <b>266</b> and raised portion <b>264</b> thus flexing prongs <b>262</b> and <b>263</b> inwards. Preferably, the sliding member is a tip portion <b>289</b> of release button <b>242</b>. Tie pin <b>240</b> is slidably received within blind hole <b>272</b> of release button <b>242</b>. The internal diameter of blind hole <b>272</b> is small enough so that when it is advanced over ramp <b>266</b> and/or raised portion <b>264</b>, prongs <b>262</b> and <b>263</b> are flexed inwards. Preferably, the entrance to blind hole <b>272</b> has an internal chamfer <b>288</b> so that ramp <b>266</b> is smoothly engaged as release button <b>242</b> is advanced.

0163Release button <b>242</b> preferably has a generally cylindrical body <b>285</b> which is slidably received within mating bore <b>294</b> (see <figref idref="DRAWINGS">FIG. 25</figref>) of mount body <b>222</b>. Release button <b>242</b> is retained in place, and its sliding travel limited, by release button flange <b>241</b> on one end and spring clip or e-clip <b>293</b> assembled within e-clip groove <b>286</b> on the other end. Spring material <b>246</b>, such as a wave spring washer or foam material, may be disposed between release button flange <b>241</b> and mount body <b>222</b> to bias release button <b>242</b> outwards. Transverse to blind hole <b>272</b> tip portion <b>289</b> also has a clearance slot <b>287</b> through which base post <b>230</b> passes.

0164For clarity only, <figref idref="DRAWINGS">FIGS. 22A–25</figref> have illustrated instrument mount assembly <b>220</b> without hinge member <b>115</b> and cam <b>145</b> attached. However, hinge member <b>115</b> having rail grip <b>116</b> is preferably pivotally mounted, with cam <b>145</b> in place, by way of pins or the like at hinge mount <b>228</b> as described above with reference to instrument mount assembly <b>20</b>. As discussed above, cam <b>145</b> may be rotated about cam guide <b>223</b> using base lever <b>122</b> to secure the instrument mount to a rail or other suitable structure.

0165The retractor and instrument mounts described above can be used to mount and stabilize a great number of instruments for use during surgery. Preferably, the retractor and instrument mounts are used to mount a mechanical stabilizer for stabilizing at least a portion of the beating heart during CABG surgery or the like. Described below are a number of mechanical stabilizer embodiments that are particularly beneficial for stabilizing the beating heart, especially when used in conjunction with the retractors and instrument mounts described above.

0166Tissue Stabilizers

0167Once access to the heart is achieved, and the heart is positioned if necessary, a means for stabilizing the beating heart is introduced through the opening created and at least one component of the stabilizing device of the invention is brought into contact with the beating heart. The surgeon then applies a stabilizing force to the beating heart via the stabilizing means which may then be fixed in place by attachment to a fixed support. When a retractor or platform is fixed in an open position to expose the heart, the retractor platform may also provide the stable support structure to which the stabilizing means is affixed. When the position of the stabilizing means is fixed by attachment to a stable support or to the retractor platform, the stabilizing force is maintained for the duration of the procedure.

0168The structure of the portion of the stabilizing means which contacts the heart may include one or more contact members which exert a stabilizing force on the heart proximate to the site of the anastomosis. A pair of contact members may be plates or rectangular members which are placed on either side of the target coronary artery at the site of the anastomosis and which may have friction means or tissue spreading or compressing apparatus associated therewith. The contact members may also be provided by a platform which may be substantially planar or which may be contoured to fit conformingly on the surface of the heart. The stabilizing means may also include a shaft means having several alternative embodiments to facilitate adjusting the position and orientation of the instrument. For example, the shaft means may have an adjustable length and the axis of the shaft means may have at least one ball joint disposed within its length such that the orientation of the shaft means relative to another structure such as the contact members or stable support may be continuously varied. As is apparent from the description of the several embodiments, each of the individual embodiments described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other several embodiments.

0169Referring to <figref idref="DRAWINGS">FIGS. 33–37</figref>, a preferred stabilizer assembly for stabilizing the beating heart is comprised of a foot or base portion <b>553</b> attached to a rigid or semi-rigid shaft means or connecting shaft <b>3</b>. Base portion <b>553</b> typically has one or more contact members <b>1</b> adapted to contact the heart adjacent the site desired to be stabilized. The contact members <b>1</b> may be substantially planar, may be slightly curved to conform to the shape of the heart, or may be a non-conforming curve to establish contact between only a portion of the contact member <b>1</b> and the beating heart. The shape of the contact members may be varied depending on the clinical assessment by the surgeon, the design of the other features of the stabilizing means, or the design of other instruments used to complete the anastomosis. In some embodiments the contact members <b>1</b> may have apertures, openings or attachments to facilitate connection with sutures or other devices to achieve the requisite stabilization, occlusion of the target vessel, or exposure of the target vessel. Examples of suitable base portions and contact members can be found, for example, in co-pending U.S. patent application Ser. No. 08/931,158 filed on Sep. 16, 1997, entitled “SURGICAL INSTRUMENTS AND PROCEDURES FOR STABILIZING THE BEATING HEART DURING CORONARY ARTERY BYPASS GRAFT SURGERY”, the entirety of which is herein incorporated by reference.

0170Referring to <figref idref="DRAWINGS">FIGS. 33 and 34</figref>, the proximal end of connecting shaft <b>3</b> has handle mechanism <b>468</b> assembled thereto which, among other things, provides the user with a means for locking an end effector operably attached to the distal end of connecting shaft <b>3</b>. The mechanism <b>468</b> is rotatably secured to the proximal end of the shaft means <b>3</b> and is formed at a selected angle to the shaft means to permit a surgeon to swivel the mechanism to a preferred position where the knob <b>504</b> is more readily accessible to allow quickly locking the shaft means <b>3</b> in the orientation selected. In addition, the angled axis of the knob <b>504</b> relative to the shaft means <b>3</b> reduces the tendency of the shaft means <b>3</b> to rotate about its axis when a surgeon applies torque to the knob <b>504</b> to lock the associated locking mechanism. The knob <b>504</b> is secured to a screw <b>539</b> by suitable means such as press fitting, bonding, etc. Right and left handle covers <b>540</b>, <b>541</b> comprise the handle <b>503</b> and provide the support for the handle mechanism. When assembled, the covers define generally a cylinder formed with a selected curvature. A secondary inner molding, generally indicated at <b>542</b>, includes various integrally formed annular walls and shoulders for supporting and containing the knob <b>504</b> and screw <b>539</b>, as well as a cooperating nut <b>543</b>, and arcuate wedge <b>544</b>, a shaft retaining ring <b>545</b>, the proximal end of the shaft means <b>3</b>, and a proximal end of the translatable pushrod <b>505</b>. The proximal end of the shaft means <b>3</b> includes an annular retaining ring slot <b>546</b> which secures the proximal end of the shaft means <b>3</b> within suitable annular walls in the corresponding end of the handle covers <b>540</b>, <b>541</b> when the retaining ring <b>545</b>, confined by shoulders in the inner molding <b>542</b>, is snapped into the slot <b>546</b> and the covers are assembled. The nut <b>543</b> is confined by shoulders in the inner molding <b>542</b>, and the arcuate wedge <b>544</b> is slidably confined by correspondingly arcuate walls <b>547</b> also formed in the inner molding.

0171As may be seen, rotation of the threaded screw <b>539</b> within the confined threaded nut <b>543</b>, causes translation of the screw, pivoting and thus translation of the translatable wedge <b>544</b> which abuts the screw, and translation of the pushrod <b>505</b> which abuts the translatable wedge. As is further described relative to <figref idref="DRAWINGS">FIGS. 35–37</figref>, any tightening or loosening of the screw <b>539</b>, however slight, will cause a corresponding translation of the pushrod <b>505</b> into or out of the shaft means <b>3</b>.

0172As depicted in the Figures, the shaft means <b>3</b> and thus the pushrod <b>505</b>, are formed with a slight arcuate configuration, which permits additional degrees of freedom and movement and orientation of the distal end of the shaft means <b>3</b> and thus of the heart contact member <b>1</b>. Rotation of the shaft means <b>3</b> about the axis of confinement within the shaft grip <b>495</b> or <b>495</b><i>a</i>, moves the distal end of the shaft means <b>3</b> through a circular path while changing the angles through which the contact member <b>1</b> can be oriented. This allows a surgeon to conveniently achieve a wider range of positions and orientations of the contact member relative to the patient's heart, while keeping the proximal end of the shaft means <b>3</b> and handle mechanism <b>468</b> out of the way as much as possible.

0173<figref idref="DRAWINGS">FIGS. 35–37</figref> illustrate an associated mechanism for maneuverably supporting the various embodiments of the contact member <b>1</b> and for cooperatively assisting in the quick locking of the contact member by a partial rotation of the knob <b>504</b> once the member is positioned. To this end, the distal end of the shaft means <b>3</b> is provided with exterior threads matching interior threads in a ball/socket <b>548</b>. The distal end of ball/socket <b>548</b> is provided with slots <b>549</b>, whereby the remaining material comprises short extended tips <b>550</b> which, when bent in or inwardly formed, form a socket. A ball/post <b>551</b> includes a ball at one end and a post at the other. When the mechanism is assembled, the ball/post <b>551</b> is inserted into place within the ball/socket <b>548</b> with the ball in the socket and the post protruding from the ball socket. A mechanism for providing a preloaded source, such as a compression spring <b>552</b>, is coupled to the ball/socket <b>548</b> abutting the ball. The spring <b>552</b> is urged by the distal end of the shaft means <b>3</b> to exert a preloaded or constant minimum force against the ball of the ball/post <b>551</b>. The post of the ball/post <b>551</b> is solidly fixed as by pressing fitting, welding, etc., to the contact member <b>1</b>. The distal end of the pushrod <b>505</b> passes through the spring <b>552</b> to abut the ball of the ball/post <b>551</b>. Thus when the screw <b>539</b> is not tightened, the distal end of the pushrod <b>505</b> exerts a slight pressure against the ball, however the spring <b>552</b> maintains a preloaded force against the ball sufficient to maintain the contact member <b>1</b> at any orientation set by a surgeon. When the screw <b>539</b> is tightened, the pushrod <b>505</b> is forced against the ball to prevent any further movement of the contact member <b>1</b>. As may be seen, the contact member <b>1</b> can be tilted to assume many orientations since the narrow center of the post can tilt into any of the four slots <b>549</b> in the ball/socket <b>548</b>. In addition, simultaneous rotation of the curved shaft means <b>3</b> provides a surgeon with an even greater variety of orientations of the contact member relative to a patient's heart.

0174The contact member <b>1</b> includes a preferred configuration which improves the size of the area of the heart which is visible to a surgeon while still providing the required suppression of heart movement necessary to enable the efficient construction of the anastomosis. More particularly, the pair of spaced-apart contact members <b>1</b> extend from a common base portion <b>553</b>, which uniquely first extends back away from the tips of the contact members at the point of attachment to the post, as shown at reference number <b>554</b>. The spaced contact members <b>1</b> then curve downward away from the common base portion <b>553</b> and back past the post and away from the shaft means <b>3</b>. As may be seen in the <figref idref="DRAWINGS">FIGS. 35–37</figref>, the contact member <b>1</b> of this embodiment uniquely is attached to the post on the same surface as the surface that bears against the surface of the beating heart. Since the members <b>1</b> separate at the base portion <b>553</b> at a point <b>555</b> behind the distal end of the shaft means <b>3</b>, a surgeon has an unobstructed and thus optimum view of the heart even below the distal end of the shaft means <b>3</b>.

0175The contact members preferably include friction means <b>556</b> selectively secured to the bottom surfaces thereof to more securely engage a beating heart. In addition, the tips of the contact members are bent upward in the form of “ski tips” to lessen their impact when the contact members are firmly pressed against a beating heart to suppress the anastomotic site.

0176Although screw means <b>539</b>/<b>504</b>/<b>543</b> is illustrated herein as a locking mechanism of the handle mechanism <b>468</b>, it is to be understood that other mechanisms may be employed. For example, a cam/lever mechanism may be attached to a rod which in turn imparts a pivoting movement or translation to a suitable bellcrank or pivotable member, which in turn imparts translation to pushrod <b>505</b> of the shaft means <b>3</b>. Thus, locking mechanisms other than those specifically described herein may be used.

0177The basic configuration as just described with reference to base portion <b>553</b> provides the maneuverability necessary to access and stabilize any desired vessel on the surface of the beating heart. However, the exact manner and position in which the stabilizer may be placed relative to the vessel and the surgical techniques preferred by an individual surgeon may vary significantly. Accordingly, there is some potential that certain combinations of stabilizer positioning may interfere somewhat with the preferred surgical technique of a particular surgeon. The embodiments illustrated below with respect to <figref idref="DRAWINGS">FIGS. 38–40B</figref> alleviate any such problems.

0178One useful variation, as illustrated in <figref idref="DRAWINGS">FIG. 38</figref>, connects connecting shaft <b>3</b> to the base portion of the stabilizer at a position which is generally offset from the center or off-center. Base portion <b>710</b> is again typically formed of a unitary piece of sheet material and has a curved back portion in which connecting shaft <b>3</b> is attached to an extension of the same surface which carries the contacting members, except that the connecting point <b>718</b>, to which ball/post <b>551</b> is attached is positioned away from the center and therefore away from the space between contact members <b>712</b> where the anastomosis would be performed. This configuration tends to ensure that connecting shaft <b>3</b> will not interfere with the surgical access to the center area of the base portion. Of course, the connection can be offset from the central region in either direction.

0179In addition, base portion <b>710</b> illustrates a number of features for improving the traction and vessel presentation during a CABG procedure on a beating heart. Contact members <b>712</b> of base member <b>710</b> have portions <b>713</b> having an increased width and which are preferably substantially flat or slightly curved to conform to the heart. This configuration provides a larger area for coined regions <b>715</b>, which represent indentations on the bottom surface for receiving a traction material, thus providing greater traction against the surface of the heart.

0180Further, base portion <b>710</b> provides a smaller open space between contact members <b>712</b>. In a preferred embodiment, the spacing <b>716</b> between contact members <b>712</b> is less than about 0.350 inches, more preferably less than about 0.300 inches, and most preferably about 0.25 inches. This minimized spacing provides stabilization closer to the vessel and, in some instances, the compressive forces applied through contact members <b>712</b> actually tend to present the vessel upwards between contact members <b>712</b> in a more favorably pronounced manner. The tip portions <b>714</b> of contact members <b>712</b> are angled upwards from the surface of the heart to minimize any possible trauma to the heart during use.

0181As just discussed, the base portions (<b>550</b> or <b>710</b>) can be manipulated or oriented relative to the end of the connecting shaft <b>3</b> by virtue of the ball and socket joint between base portion <b>553</b> and connecting shaft <b>3</b>. The amount of angular manipulation or travel available is somewhat limited as ball/post <b>551</b> eventually bottoms out or stops against either the bottom of slots <b>549</b> or extended tips <b>550</b>. Thus, the contact members have a limited range of movement relative to connecting shaft <b>3</b> based upon the nominal mounting relationship between the contact members and the ball/post. Accordingly, for some procedures, it may be desirable to have a different nominal relationship between the contact members and the ball/post to shaft connection.

0182Referring to <figref idref="DRAWINGS">FIGS. 39–40B</figref>, base member <b>720</b> illustrates an alternative orientation of ball/post <b>551</b>. Instead of being angled away from the contact members, base member <b>720</b> has a back portion <b>721</b> which allows ball/socket <b>551</b> to be mounted generally parallel to contact members <b>722</b>. Ball/post <b>551</b> preferably extend towards contact members <b>722</b> as shown, but may also extend the opposite direction away from the contact members. The connecting point <b>723</b> is preferably offset a distance <b>724</b> from the central area between the contact members <b>722</b>. The connecting point <b>723</b> is also off set a greater distance <b>726</b> from the contacting place of contact members <b>722</b>. In nominal position of base portion <b>722</b> relative to ball/post <b>551</b>, this configuration tends to keep the connecting shaft <b>3</b> clear from the central portion between contact members <b>722</b>. Furthermore, relative to connecting shaft <b>3</b>, contact members <b>722</b> can be maneuvered through a range of motion different from base member <b>553</b> due to the initial orientation of ball/post <b>551</b>. Because the preferred location of the attachment of the connecting shaft <b>3</b> to the base portion may be different from surgeon to surgeon and from procedure to procedure, it may be desirable to have the ball/post moveable to more than one location. In one embodiment shown in <figref idref="DRAWINGS">FIG. 41</figref>, for example, ball/post <b>562</b> has threaded end <b>561</b> which may be threaded into any desired threaded receiving hole <b>563</b> provided in stabilizer base <b>560</b>. Ball post <b>564</b> is preferably provided with one or more flats <b>564</b> on the exterior thereof to facilitate tightening or loosening of the threaded connection. In the embodiment shown, stabilizer base <b>560</b> has threaded receiving holes <b>563</b> to provide center, offset right, and offset left connecting positions.

0183Referring to <figref idref="DRAWINGS">FIGS. 42 and 43</figref>, ball/post <b>572</b> may be captured within slot <b>571</b> formed in stabilizer base <b>570</b>. Slot <b>571</b> preferably has two or more positions where the ball/post can be positively locked. In a preferred embodiment, slot <b>571</b> preferably has two or more key-hole openings <b>573</b>. Key openings <b>573</b> are sized to receive first post portion <b>577</b> having an outside diameter which closely matches the inside dimension of key opening <b>573</b>. First post portion <b>577</b> of ball/post <b>572</b> is released from key hole <b>573</b> by pulling ball post in the direction indicated by arrow <b>579</b> until second post portion <b>578</b> is positioned within keyhole <b>573</b>. Second post portion <b>578</b> is sized to have an outside diameter small enough to fit and traverse through slot <b>571</b>. Ball/post <b>572</b> may then be traversed along the path defined by slot <b>571</b> until the next desired key hole is reached, which may then be engaged by first post portion <b>577</b> to secure ball/post <b>572</b> in position on stabilizer base <b>570</b>.

0184First post portion <b>577</b> may be kept in engagement with keyholes <b>573</b> by any convenient manner. For example, ball/post <b>572</b> may be spring biased in the locked position between upper flange <b>574</b> and lower flange <b>575</b>, preferably using spring washers <b>576</b> as shown. Ball/post <b>572</b> may also be locked into operating position within keyholes <b>573</b> by using a retaining or locking clip, such as locking clip <b>580</b> illustrated with reference to <figref idref="DRAWINGS">FIGS. 44 and 45</figref>. Locking clip <b>580</b> has slot <b>584</b> adapted to slide over second post portion <b>578</b>. Locking clip <b>580</b> includes a thin portion <b>585</b>, a thick portion <b>583</b>, a transition ramp <b>582</b> between thin portion <b>585</b> and thick portion <b>583</b>, and a grip or handle portion <b>581</b>. With locking clip <b>580</b> in the open position shown in <figref idref="DRAWINGS">FIG. 44</figref>, ball post <b>572</b> is free to move upwards in the direction of arrow <b>579</b>, thus releasing first post portion <b>577</b> from key hole <b>573</b>. When locking clip <b>580</b> is moved in the direction indicated by arrow <b>586</b>, the outer thickness of thick portion <b>583</b> is wedged between lower flange <b>575</b> and stabilizer base <b>570</b>, thus locking ball/post <b>572</b> in place within keyhole <b>573</b>.

0185Stabilizer base <b>590</b> in <figref idref="DRAWINGS">FIG. 46</figref> has ball/post <b>592</b> mounted to an articulating member which is moveable between two or more positions. Preferably, ball/post <b>592</b> is mounted on first end <b>594</b> of pivoting link <b>591</b> which is pivotably attached to stabilizer base <b>590</b> at pivot pin <b>596</b>. Preferably, pivot pin <b>596</b> is centrally located on pivoting link <b>591</b>. At second end <b>593</b> of pivoting link <b>591</b>, a locking knob <b>595</b> may be provided to engage stabilizer base <b>590</b>. Preferably, locking knob <b>595</b> has a threaded shaft or other such fastening or locking feature which engages mating threaded holes (typically one positioned under locking knob <b>595</b> and one under ball/post <b>592</b>) in stabilizer base <b>590</b>. The ball/post <b>592</b> and locking knob <b>595</b> are preferably spaced equal distances from pivot pin <b>596</b> such that when pivoting link <b>591</b> is rotated as indicated by arrow <b>597</b>, the position of ball/post <b>592</b> and locking knob <b>595</b> are reversed.

0186Another embodiment of a tissue stabilizer having an adjustable attachment position of the connecting shaft is illustrated in <figref idref="DRAWINGS">FIGS. 47–50</figref>. Stabilizer base assembly <b>625</b> includes top member <b>605</b> and stabilizer base <b>600</b>, having contact members <b>606</b> and <b>607</b> and notch or relief <b>603</b> under which a vessel may safely pass without being occluded. At least a portion of stabilizer base <b>600</b> has outer profile <b>601</b> which is generally curved or circular at a predetermined radius. Top member <b>605</b> has a mating interior curvature such that stabilizer base <b>600</b> and top member <b>605</b> concentrically rotate relative to each other, preferably about a common center point. Ball/post <b>602</b> may be attached at a convenient position, typically centered, on top member <b>605</b>. Rotation of top member <b>605</b> relative to stabilizer base <b>600</b>, as indicated by arrows <b>620</b> and <b>619</b>, thus adjusts the position of ball/post <b>602</b> along an arcuate path relative to contact members <b>606</b> and <b>607</b>.

0187To facilitate the secure attachment and smooth rotation of top member <b>605</b> relative to stabilizer base <b>600</b>, top member <b>605</b> may be provided with one or more projections adapted to be received within guide slots provided in stabilizer base <b>600</b>. In a preferred embodiment, top member <b>605</b> has side projections or rails <b>608</b> and <b>609</b> which snap into lower slots or channels <b>611</b> and <b>610</b> in stabilizer base <b>600</b> as top member <b>605</b> is urged into a concentric position over stabilizer base <b>600</b>. Rails <b>608</b> and <b>609</b> slide within channel <b>611</b> and <b>610</b> to maintain a secure attachment and controlled rotation of top member <b>605</b> and stabilizer base <b>600</b>. Top member <b>605</b> may optionally have tab <b>612</b> adapted to be received within upper slot <b>604</b> on stabilizer base <b>600</b>. Upper slot <b>604</b> may have a plurality of detents or teeth which form a desired number of detented positions as tab <b>612</b> is rotated around the path of upper slot <b>604</b>. In a preferred embodiment, detented position <b>617</b> is formed between tooth <b>613</b> and slot end <b>616</b> and detented position <b>618</b> is formed between tooth <b>614</b> and tooth <b>615</b>. Of course, detented positions may be created at any desired location using a variety of alternate constructions. Preferably, the detent action of tab <b>612</b> allows the operator to manually select a position of ball/post <b>602</b>, but then holds the position of top member <b>605</b> relative to stabilizer base <b>600</b> against movement during use to ensure effective stabilization of a target vessel on the beating heart.

0188In addition to the critical function of stabilizing the beating heart, it is also important for the tissue stabilizer to present the stabilized coronary artery in a manner which allows sutures to be easily placed around the mouth of the arteriotomy as required to create the anastomosis. <figref idref="DRAWINGS">FIGS. 51A–54</figref> illustrate a tissue stabilizer embodiment involving a base portion having a single contacting surface for stabilizing a target vessel on the beating heart and a mechanical bail element to facilitate optimal vessel presentation.

0189Referring to <figref idref="DRAWINGS">FIGS. 51A and 51B</figref> stabilizer base <b>740</b> is shown attached to connecting shaft <b>3</b> using ball/post <b>730</b>. Connecting shaft <b>3</b> is shown connected generally to the center of stabilizer base <b>740</b> at approximately a right angle, however, as discussed above, the ball/post <b>730</b> could be connected at any desired offset or orientation or the position of ball/post <b>730</b> could be adjustable. Stabilizer base <b>740</b> preferably has a single contacting surface <b>742</b> which may be flat or curved to at least partially conform to the surface of the heart. Contacting surface <b>742</b> is sized to provide sufficient contacting area such that sufficient compressive force can be applied to the beating heart to achieve effective immobilization or stabilization of a target coronary artery.

0190Stablizer base <b>740</b> preferably has an extending frame member or bail <b>745</b> attached thereto. Bail <b>745</b> may be a thin, round or square cross-sectioned member, and is preferably a stainless steel wire. Bail <b>740</b> has a bail portion <b>756</b> which is generally parallel to stabilizer base <b>740</b> and may have relieved sections <b>747</b> formed therein so as not to occlude the vessel during use. Bail portion <b>756</b> may have tissue gripping features, such as teeth <b>755</b>. In an optional embodiment, bail portion <b>756</b> may be provided with rotating cover or a spiral wound thread (not shown) so that bail portion may be more easily repositioned, under a stabilizing load, over the surface of the heart as discussed below.

0191In a preferred embodiment, bail <b>745</b> is moveable relative to stabilizer base <b>740</b>. Bail <b>745</b> can be moved in or out in the direction indicated by arrow <b>750</b> to cause bail section <b>756</b>, which is generally parallel with stabilizer base <b>740</b>, to compress tissue towards stabilizer base <b>740</b> or stretch tissue away from stabilizer base <b>740</b>. Thus, bail <b>745</b> can be moved in and out to compress or stretch the tissue surrounding a coronary artery until the optimum presentation for performing the anastomosis is achieved. The generally parallel portion may be vertically offset from contacting surface <b>742</b> by a distance <b>757</b> which is typically about 0.050 inches to about 0.200 inches.

0192Although bail <b>745</b> may be attached in a number of ways, bail <b>745</b> is preferably formed with first and second end portions <b>748</b> and <b>749</b> having detents or teeth <b>746</b>. Stabilizer base <b>740</b> preferably has channels <b>751</b> and <b>752</b> for receiving end portions <b>749</b> and <b>748</b> respectively. Channels <b>751</b> and <b>752</b> preferably have internal mating teeth <b>753</b> for engaging teeth <b>746</b>. End portions <b>748</b> and <b>749</b> can be incrementally advanced into channels <b>752</b> and <b>751</b> as teeth <b>746</b> deflect and release from a mated position relative to teeth <b>753</b> and then successively engage the next mated position. Stabilizer base <b>740</b> may include cover <b>754</b> over channels <b>751</b> and <b>752</b>. So that the stabilizer can be removed from around a completed anastomosis, at least one end of bail <b>745</b> is detachable from stabilizer base <b>740</b>. In a preferred embodiment, stabilizer base <b>740</b> is substantially symmetrical allowing bail <b>745</b> to be assembled from either side in a right or left handed configuration.

0193Bail <b>745</b> is preferably flexible or semi-flexible relative to stabilizer base <b>740</b>. As a result of its inherent flexibility, bail <b>745</b> applies a predetermined force against the heart that, under operating conditions, may be generally independent of the stabilizing force applied to stabilizer base <b>740</b> to stabilize the beating heart. That is, once stabilizer base <b>740</b> is forced against the surface of the heart, the force applied by bail <b>745</b> is a function of its mechanical spring rate relative to stabilizer base <b>740</b>.

0194<figref idref="DRAWINGS">FIGS. 52A and 52B</figref> illustrate another single contact stabilizer base having a bail <b>762</b> which is secured at only one end. Stabilizer base <b>760</b> may have a housing <b>765</b> having a series of internal teeth (not shown). Bail <b>762</b> has a toothed end <b>766</b> which is received within housing <b>765</b> to engage with the mating teeth provided therein. As with the embodiment above, bail <b>762</b> has a generally parallel portion <b>763</b> which is moveable relative to stabilizer base <b>760</b> in the direction generally indicated by arrow <b>767</b> to stretch or compress the surrounding tissue for optimum vessel presentation. Bail <b>762</b> may have tab <b>761</b> to facilitate grasping by an instrument, such as for example forceps <b>761</b>. The free end <b>764</b> of bail <b>762</b> is preferably rounded or somewhat bulbous so as to be atraumatic. Because bail <b>762</b> attaches only at one end, the stabilizer can be easily removed from the completed anastomosis without removing bail <b>762</b> from stabilizer base <b>760</b>.

0195In another embodiment of the stabilizer, the wire frame member or bail may have a drive mechanism for moving the bail relative to the stabilizer base. Referring to <figref idref="DRAWINGS">FIG. 53</figref> stabilizer base <b>770</b> has housing <b>771</b> which is constructed with guide channel <b>774</b> having gear <b>775</b> mounted for rotation therein. Bail <b>772</b> has a toothed end <b>773</b> which may be assembled within guide channel <b>774</b> such that rotation of gear <b>775</b> causes bail <b>772</b> to be moved in and out in the direction indicated by arrow <b>43</b>. Gear <b>775</b> may be driven by any suitable tool, for example, gear <b>775</b> may have a drive hole <b>778</b> for engagement by a suitable drive tool <b>771</b>.

0196Another driven bail stabilizer is shown in <figref idref="DRAWINGS">FIG. 54</figref>. In this embodiment, stabilizer base <b>780</b> has threaded shaft <b>781</b> preferably supported at its end portions by bushings or bearings <b>783</b> and <b>784</b>. One end of the threaded shaft is connected to a flexible drive <b>785</b> through a flexible or universal joint <b>791</b>. The flexible drive may be routed up connecting shaft <b>3</b>. Preferably flexible drive <b>785</b> is secured to connecting shaft <b>3</b> by way of a thin polymeric coating. Bail <b>782</b> is connected to threaded collar <b>787</b> which cooperates with threaded shaft <b>781</b> to move bail in and out relative to stabilizer base <b>780</b> in the general direction indicated by arrow <b>790</b>. The screw and collar drive mechanism is preferably concealed by housing <b>788</b> which has only a small slotted opening <b>786</b> allowing passage of bail <b>782</b>.

0197With each of the flexible bail embodiments described above, stabilization and vessel presentation are relatively independent. First, the beating heart is typically stabilized using a compressive force delivered by way of the single contacting surface provided by the stabilizer base. The bail may then be manipulated in or out to obtain the optimum presentation of the vessel for whatever surgical procedure is underway. For example, one bail position may be optimal for creating the arteriotomy, another bail position for insertion of a shunt or like device (should one be used), another bail position for creating the anastomosis, and so on. All the while, the stabilization of the beating heart itself remains optimized by the contacting surface of the stabilizer base.

0198The Stabilization System

0199Preferred embodiments for each of the retractor, the instrument mount and the tissue stabilizers have been discussed in detail above. While each component may be utilized separately, superior access and stabilization can be achieved when the multiple components are used together for performing a minimally invasive cardiac surgery, preferably through a sternotomy approach. Referring to <figref idref="DRAWINGS">FIG. 55</figref>, retractor assembly <b>900</b>, including drive mechanism <b>910</b> and first and second platform blades <b>915</b> and <b>920</b>, may be used to spread the sternum, providing access and direct visualization to the thoracic cavity. Retractor assembly <b>900</b> also allows sutures to be fixed or organized. Stabilizer assembly <b>800</b> isolates and provides local immobilization of the target vessel on the beating heart. Instrument mount assembly <b>850</b> facilitates precise maneuvering of the stabilizer and ensures a stable, motion free mount at the desired position and orientation.

0200To begin a typical beating heart CABG procedure using the preferred stabilization system illustrated in <figref idref="DRAWINGS">FIG. 55</figref>, drive mechanism <b>910</b> is preferably placed in the fully closed position with moveable housing <b>925</b> positioned against or adjacent fixed housing <b>930</b>. First platform blade <b>915</b> is then assembled to moveable housing <b>925</b> and a second platform blade <b>920</b> is assembled to fixed housing <b>930</b>. After ensuring that platform blades <b>915</b> and <b>920</b> are fully and securely attached to drive mechanism <b>910</b>, engaging members <b>935</b> of platform blades <b>915</b> and <b>920</b> are securely seated on the incised sternum created using standard surgical procedures. Drive handle <b>940</b> may then be rotated clockwise to separate platform blades <b>915</b> and <b>920</b>, thus creating the desired opening for accessing the beating heart.

0201If positioning the heart using sutures to position the heart, the sutures may be placed through the tissue at the desired location and secured to platform blades <b>915</b> and <b>920</b>. Sutures <b>945</b> may be slid into suture holder slots <b>950</b> to engage the suture. To ensure proper a proper hold, only one suture strand is preferably engaged within each suture holder slot <b>950</b>. Sutures <b>945</b> are released from platform blades <b>915</b> and <b>920</b> by concurrently pulling back and up on suture <b>945</b> while pulling the suture through the suture holder slot <b>950</b>.

0202With the heart positioned as desired, instrument mount assembly <b>850</b> may be assembled to platform blade <b>920</b> (or <b>915</b>) by hooking stabilizer mount base <b>955</b> onto rail <b>960</b> (or <b>961</b>) at the desired location and moving the base lever (not visible in this view) clockwise to the closed position to secure instrument mount assembly <b>850</b> onto rail <b>960</b>. Mount body <b>110</b> may be oriented to the desired angle by way of ball joint <b>965</b> and locked into place by turning the top mount knob <b>855</b> clockwise.

0203Stabilizer base <b>810</b>, having contact members <b>812</b> and <b>814</b>, may then be positioned on the epicardium of the beating heart by gently lowering connecting shaft <b>820</b> using one hand to guide stabilizer base <b>810</b> onto the target area on the heart. Incremental pressure is applied to stabilizer base <b>810</b> situated on the epicardium until the desired immobilization or stabilization is achieved. Connecting shaft <b>820</b> is secured in the desired position by turning side mount knob <b>860</b> clockwise and stabilizer base <b>810</b> is secured in the desired position relative to connecting shaft <b>820</b> by turning the stabilizer shaft knob <b>830</b> clockwise. With the beating heart stabilized the anastomosis, or other desired procedure, is completed.

0204To remove stabilizer base <b>810</b>, connecting shaft <b>820</b> is held with one hand while side mount knob <b>860</b> is loosened with the other hand. Stabilizer base <b>810</b> is then carefully removed from the anastomotic site. The base lever is moved to the open position to release instrument mount assembly <b>850</b>, and stabilizer assembly <b>800</b> mounted thereto, from rail <b>960</b> on platform blade <b>920</b>. When the entire bypass procedure is completed, drive handle <b>940</b> is rotated in the counter clockwise direction to close drive mechaninsm <b>910</b> and platform blades <b>915</b> and <b>920</b>. Retractor assembly <b>900</b> may then be gently removed from the access incision. To remove platform blades <b>915</b> and <b>920</b> from moveable housing <b>925</b> and fixed housing <b>930</b>, respectively, release latches <b>970</b> are manually activated and platform blades <b>915</b> and <b>920</b> may be pulled generally straight away from drive mechanism <b>910</b>. Drive mechanism <b>910</b> may then be sterilized and prepared for use in a subsequent procedure.

0205While certain embodiments are illustrated in the drawings and have just been described herein, it will be apparent to those skilled in the art that many modifications can be made to the embodiments without departing from the inventive concepts described. For purposes of illustration only, the principles of the present invention has been generally described with reference to a coronary artery bypass procedure, but may readily be applied to other types surgical procedures not specifically described. Many other uses are well-known in the art, and the concepts described herein are equally applicable to those other uses. Further, the different components of the various exemplar embodiments described above can be combined in any desirable construction. Accordingly, the invention is not to be restricted except by the claims which follow.